xref: /petsc/src/mat/impls/aij/seq/aijfact.c (revision 609bdbee21ea3be08735c64dbe00a9ab27759925)
1 
2 #include <../src/mat/impls/aij/seq/aij.h>
3 #include <../src/mat/impls/sbaij/seq/sbaij.h>
4 #include <petscbt.h>
5 #include <../src/mat/utils/freespace.h>
6 
7 /*
8       Computes an ordering to get most of the large numerical values in the lower triangular part of the matrix
9 
10       This code does not work and is not called anywhere. It would be registered with MatOrderingRegisterAll()
11 */
12 PetscErrorCode MatGetOrdering_Flow_SeqAIJ(Mat mat,MatOrderingType type,IS *irow,IS *icol)
13 {
14   Mat_SeqAIJ        *a = (Mat_SeqAIJ*)mat->data;
15   PetscErrorCode    ierr;
16   PetscInt          i,j,jj,k, kk,n = mat->rmap->n, current = 0, newcurrent = 0,*order;
17   const PetscInt    *ai = a->i, *aj = a->j;
18   const PetscScalar *aa = a->a;
19   PetscBool         *done;
20   PetscReal         best,past = 0,future;
21 
22   PetscFunctionBegin;
23   /* pick initial row */
24   best = -1;
25   for (i=0; i<n; i++) {
26     future = 0.0;
27     for (j=ai[i]; j<ai[i+1]; j++) {
28       if (aj[j] != i) future += PetscAbsScalar(aa[j]);
29       else              past  = PetscAbsScalar(aa[j]);
30     }
31     if (!future) future = 1.e-10; /* if there is zero in the upper diagonal part want to rank this row high */
32     if (past/future > best) {
33       best    = past/future;
34       current = i;
35     }
36   }
37 
38   ierr     = PetscMalloc1(n,&done);CHKERRQ(ierr);
39   ierr     = PetscMemzero(done,n*sizeof(PetscBool));CHKERRQ(ierr);
40   ierr     = PetscMalloc1(n,&order);CHKERRQ(ierr);
41   order[0] = current;
42   for (i=0; i<n-1; i++) {
43     done[current] = PETSC_TRUE;
44     best          = -1;
45     /* loop over all neighbors of current pivot */
46     for (j=ai[current]; j<ai[current+1]; j++) {
47       jj = aj[j];
48       if (done[jj]) continue;
49       /* loop over columns of potential next row computing weights for below and above diagonal */
50       past = future = 0.0;
51       for (k=ai[jj]; k<ai[jj+1]; k++) {
52         kk = aj[k];
53         if (done[kk]) past += PetscAbsScalar(aa[k]);
54         else if (kk != jj) future += PetscAbsScalar(aa[k]);
55       }
56       if (!future) future = 1.e-10; /* if there is zero in the upper diagonal part want to rank this row high */
57       if (past/future > best) {
58         best       = past/future;
59         newcurrent = jj;
60       }
61     }
62     if (best == -1) { /* no neighbors to select from so select best of all that remain */
63       best = -1;
64       for (k=0; k<n; k++) {
65         if (done[k]) continue;
66         future = 0.0;
67         past   = 0.0;
68         for (j=ai[k]; j<ai[k+1]; j++) {
69           kk = aj[j];
70           if (done[kk])       past += PetscAbsScalar(aa[j]);
71           else if (kk != k) future += PetscAbsScalar(aa[j]);
72         }
73         if (!future) future = 1.e-10; /* if there is zero in the upper diagonal part want to rank this row high */
74         if (past/future > best) {
75           best       = past/future;
76           newcurrent = k;
77         }
78       }
79     }
80     if (current == newcurrent) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"newcurrent cannot be current");
81     current    = newcurrent;
82     order[i+1] = current;
83   }
84   ierr  = ISCreateGeneral(PETSC_COMM_SELF,n,order,PETSC_COPY_VALUES,irow);CHKERRQ(ierr);
85   *icol = *irow;
86   ierr  = PetscObjectReference((PetscObject)*irow);CHKERRQ(ierr);
87   ierr  = PetscFree(done);CHKERRQ(ierr);
88   ierr  = PetscFree(order);CHKERRQ(ierr);
89   PetscFunctionReturn(0);
90 }
91 
92 PETSC_INTERN PetscErrorCode MatGetFactor_seqaij_petsc(Mat A,MatFactorType ftype,Mat *B)
93 {
94   PetscInt       n = A->rmap->n;
95   PetscErrorCode ierr;
96 
97   PetscFunctionBegin;
98 #if defined(PETSC_USE_COMPLEX)
99   if (A->hermitian && (ftype == MAT_FACTOR_CHOLESKY || ftype == MAT_FACTOR_ICC)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Hermitian Factor is not supported");
100 #endif
101   ierr = MatCreate(PetscObjectComm((PetscObject)A),B);CHKERRQ(ierr);
102   ierr = MatSetSizes(*B,n,n,n,n);CHKERRQ(ierr);
103   if (ftype == MAT_FACTOR_LU || ftype == MAT_FACTOR_ILU || ftype == MAT_FACTOR_ILUDT) {
104     ierr = MatSetType(*B,MATSEQAIJ);CHKERRQ(ierr);
105 
106     (*B)->ops->ilufactorsymbolic = MatILUFactorSymbolic_SeqAIJ;
107     (*B)->ops->lufactorsymbolic  = MatLUFactorSymbolic_SeqAIJ;
108 
109     ierr = MatSetBlockSizesFromMats(*B,A,A);CHKERRQ(ierr);
110   } else if (ftype == MAT_FACTOR_CHOLESKY || ftype == MAT_FACTOR_ICC) {
111     ierr = MatSetType(*B,MATSEQSBAIJ);CHKERRQ(ierr);
112     ierr = MatSeqSBAIJSetPreallocation(*B,1,MAT_SKIP_ALLOCATION,NULL);CHKERRQ(ierr);
113 
114     (*B)->ops->iccfactorsymbolic      = MatICCFactorSymbolic_SeqAIJ;
115     (*B)->ops->choleskyfactorsymbolic = MatCholeskyFactorSymbolic_SeqAIJ;
116   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Factor type not supported");
117   (*B)->factortype = ftype;
118 
119   ierr = PetscFree((*B)->solvertype);CHKERRQ(ierr);
120   ierr = PetscStrallocpy(MATSOLVERPETSC,&(*B)->solvertype);CHKERRQ(ierr);
121   PetscFunctionReturn(0);
122 }
123 
124 PetscErrorCode MatLUFactorSymbolic_SeqAIJ_inplace(Mat B,Mat A,IS isrow,IS iscol,const MatFactorInfo *info)
125 {
126   Mat_SeqAIJ         *a = (Mat_SeqAIJ*)A->data,*b;
127   IS                 isicol;
128   PetscErrorCode     ierr;
129   const PetscInt     *r,*ic;
130   PetscInt           i,n=A->rmap->n,*ai=a->i,*aj=a->j;
131   PetscInt           *bi,*bj,*ajtmp;
132   PetscInt           *bdiag,row,nnz,nzi,reallocs=0,nzbd,*im;
133   PetscReal          f;
134   PetscInt           nlnk,*lnk,k,**bi_ptr;
135   PetscFreeSpaceList free_space=NULL,current_space=NULL;
136   PetscBT            lnkbt;
137   PetscBool          missing;
138 
139   PetscFunctionBegin;
140   if (A->rmap->N != A->cmap->N) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"matrix must be square");
141   ierr = MatMissingDiagonal(A,&missing,&i);CHKERRQ(ierr);
142   if (missing) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Matrix is missing diagonal entry %D",i);
143 
144   ierr = ISInvertPermutation(iscol,PETSC_DECIDE,&isicol);CHKERRQ(ierr);
145   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
146   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
147 
148   /* get new row pointers */
149   ierr  = PetscMalloc1(n+1,&bi);CHKERRQ(ierr);
150   bi[0] = 0;
151 
152   /* bdiag is location of diagonal in factor */
153   ierr     = PetscMalloc1(n+1,&bdiag);CHKERRQ(ierr);
154   bdiag[0] = 0;
155 
156   /* linked list for storing column indices of the active row */
157   nlnk = n + 1;
158   ierr = PetscLLCreate(n,n,nlnk,lnk,lnkbt);CHKERRQ(ierr);
159 
160   ierr = PetscMalloc2(n+1,&bi_ptr,n+1,&im);CHKERRQ(ierr);
161 
162   /* initial FreeSpace size is f*(ai[n]+1) */
163   f             = info->fill;
164   ierr          = PetscFreeSpaceGet(PetscRealIntMultTruncate(f,ai[n]+1),&free_space);CHKERRQ(ierr);
165   current_space = free_space;
166 
167   for (i=0; i<n; i++) {
168     /* copy previous fill into linked list */
169     nzi = 0;
170     nnz = ai[r[i]+1] - ai[r[i]];
171     ajtmp = aj + ai[r[i]];
172     ierr  = PetscLLAddPerm(nnz,ajtmp,ic,n,nlnk,lnk,lnkbt);CHKERRQ(ierr);
173     nzi  += nlnk;
174 
175     /* add pivot rows into linked list */
176     row = lnk[n];
177     while (row < i) {
178       nzbd  = bdiag[row] - bi[row] + 1;   /* num of entries in the row with column index <= row */
179       ajtmp = bi_ptr[row] + nzbd;   /* points to the entry next to the diagonal */
180       ierr  = PetscLLAddSortedLU(ajtmp,row,nlnk,lnk,lnkbt,i,nzbd,im);CHKERRQ(ierr);
181       nzi  += nlnk;
182       row   = lnk[row];
183     }
184     bi[i+1] = bi[i] + nzi;
185     im[i]   = nzi;
186 
187     /* mark bdiag */
188     nzbd = 0;
189     nnz  = nzi;
190     k    = lnk[n];
191     while (nnz-- && k < i) {
192       nzbd++;
193       k = lnk[k];
194     }
195     bdiag[i] = bi[i] + nzbd;
196 
197     /* if free space is not available, make more free space */
198     if (current_space->local_remaining<nzi) {
199       nnz  = PetscIntMultTruncate(n - i,nzi); /* estimated and max additional space needed */
200       ierr = PetscFreeSpaceGet(nnz,&current_space);CHKERRQ(ierr);
201       reallocs++;
202     }
203 
204     /* copy data into free space, then initialize lnk */
205     ierr = PetscLLClean(n,n,nzi,lnk,current_space->array,lnkbt);CHKERRQ(ierr);
206 
207     bi_ptr[i]                       = current_space->array;
208     current_space->array           += nzi;
209     current_space->local_used      += nzi;
210     current_space->local_remaining -= nzi;
211   }
212 #if defined(PETSC_USE_INFO)
213   if (ai[n] != 0) {
214     PetscReal af = ((PetscReal)bi[n])/((PetscReal)ai[n]);
215     ierr = PetscInfo3(A,"Reallocs %D Fill ratio:given %g needed %g\n",reallocs,(double)f,(double)af);CHKERRQ(ierr);
216     ierr = PetscInfo1(A,"Run with -pc_factor_fill %g or use \n",(double)af);CHKERRQ(ierr);
217     ierr = PetscInfo1(A,"PCFactorSetFill(pc,%g);\n",(double)af);CHKERRQ(ierr);
218     ierr = PetscInfo(A,"for best performance.\n");CHKERRQ(ierr);
219   } else {
220     ierr = PetscInfo(A,"Empty matrix\n");CHKERRQ(ierr);
221   }
222 #endif
223 
224   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
225   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
226 
227   /* destroy list of free space and other temporary array(s) */
228   ierr = PetscMalloc1(bi[n]+1,&bj);CHKERRQ(ierr);
229   ierr = PetscFreeSpaceContiguous(&free_space,bj);CHKERRQ(ierr);
230   ierr = PetscLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
231   ierr = PetscFree2(bi_ptr,im);CHKERRQ(ierr);
232 
233   /* put together the new matrix */
234   ierr = MatSeqAIJSetPreallocation_SeqAIJ(B,MAT_SKIP_ALLOCATION,NULL);CHKERRQ(ierr);
235   ierr = PetscLogObjectParent((PetscObject)B,(PetscObject)isicol);CHKERRQ(ierr);
236   b    = (Mat_SeqAIJ*)(B)->data;
237 
238   b->free_a       = PETSC_TRUE;
239   b->free_ij      = PETSC_TRUE;
240   b->singlemalloc = PETSC_FALSE;
241 
242   ierr    = PetscMalloc1(bi[n]+1,&b->a);CHKERRQ(ierr);
243   b->j    = bj;
244   b->i    = bi;
245   b->diag = bdiag;
246   b->ilen = 0;
247   b->imax = 0;
248   b->row  = isrow;
249   b->col  = iscol;
250   ierr    = PetscObjectReference((PetscObject)isrow);CHKERRQ(ierr);
251   ierr    = PetscObjectReference((PetscObject)iscol);CHKERRQ(ierr);
252   b->icol = isicol;
253   ierr    = PetscMalloc1(n+1,&b->solve_work);CHKERRQ(ierr);
254 
255   /* In b structure:  Free imax, ilen, old a, old j.  Allocate solve_work, new a, new j */
256   ierr     = PetscLogObjectMemory((PetscObject)B,(bi[n]-n)*(sizeof(PetscInt)+sizeof(PetscScalar)));CHKERRQ(ierr);
257   b->maxnz = b->nz = bi[n];
258 
259   (B)->factortype            = MAT_FACTOR_LU;
260   (B)->info.factor_mallocs   = reallocs;
261   (B)->info.fill_ratio_given = f;
262 
263   if (ai[n]) {
264     (B)->info.fill_ratio_needed = ((PetscReal)bi[n])/((PetscReal)ai[n]);
265   } else {
266     (B)->info.fill_ratio_needed = 0.0;
267   }
268   (B)->ops->lufactornumeric = MatLUFactorNumeric_SeqAIJ_inplace;
269   if (a->inode.size) {
270     (B)->ops->lufactornumeric = MatLUFactorNumeric_SeqAIJ_Inode_inplace;
271   }
272   PetscFunctionReturn(0);
273 }
274 
275 PetscErrorCode MatLUFactorSymbolic_SeqAIJ(Mat B,Mat A,IS isrow,IS iscol,const MatFactorInfo *info)
276 {
277   Mat_SeqAIJ         *a = (Mat_SeqAIJ*)A->data,*b;
278   IS                 isicol;
279   PetscErrorCode     ierr;
280   const PetscInt     *r,*ic,*ai=a->i,*aj=a->j,*ajtmp;
281   PetscInt           i,n=A->rmap->n;
282   PetscInt           *bi,*bj;
283   PetscInt           *bdiag,row,nnz,nzi,reallocs=0,nzbd,*im;
284   PetscReal          f;
285   PetscInt           nlnk,*lnk,k,**bi_ptr;
286   PetscFreeSpaceList free_space=NULL,current_space=NULL;
287   PetscBT            lnkbt;
288   PetscBool          missing;
289 
290   PetscFunctionBegin;
291   if (A->rmap->N != A->cmap->N) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"matrix must be square");
292   ierr = MatMissingDiagonal(A,&missing,&i);CHKERRQ(ierr);
293   if (missing) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Matrix is missing diagonal entry %D",i);
294 
295   ierr = ISInvertPermutation(iscol,PETSC_DECIDE,&isicol);CHKERRQ(ierr);
296   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
297   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
298 
299   /* get new row and diagonal pointers, must be allocated separately because they will be given to the Mat_SeqAIJ and freed separately */
300   ierr  = PetscMalloc1(n+1,&bi);CHKERRQ(ierr);
301   ierr  = PetscMalloc1(n+1,&bdiag);CHKERRQ(ierr);
302   bi[0] = bdiag[0] = 0;
303 
304   /* linked list for storing column indices of the active row */
305   nlnk = n + 1;
306   ierr = PetscLLCreate(n,n,nlnk,lnk,lnkbt);CHKERRQ(ierr);
307 
308   ierr = PetscMalloc2(n+1,&bi_ptr,n+1,&im);CHKERRQ(ierr);
309 
310   /* initial FreeSpace size is f*(ai[n]+1) */
311   f             = info->fill;
312   ierr          = PetscFreeSpaceGet(PetscRealIntMultTruncate(f,ai[n]+1),&free_space);CHKERRQ(ierr);
313   current_space = free_space;
314 
315   for (i=0; i<n; i++) {
316     /* copy previous fill into linked list */
317     nzi = 0;
318     nnz = ai[r[i]+1] - ai[r[i]];
319     ajtmp = aj + ai[r[i]];
320     ierr  = PetscLLAddPerm(nnz,ajtmp,ic,n,nlnk,lnk,lnkbt);CHKERRQ(ierr);
321     nzi  += nlnk;
322 
323     /* add pivot rows into linked list */
324     row = lnk[n];
325     while (row < i) {
326       nzbd  = bdiag[row] + 1; /* num of entries in the row with column index <= row */
327       ajtmp = bi_ptr[row] + nzbd; /* points to the entry next to the diagonal */
328       ierr  = PetscLLAddSortedLU(ajtmp,row,nlnk,lnk,lnkbt,i,nzbd,im);CHKERRQ(ierr);
329       nzi  += nlnk;
330       row   = lnk[row];
331     }
332     bi[i+1] = bi[i] + nzi;
333     im[i]   = nzi;
334 
335     /* mark bdiag */
336     nzbd = 0;
337     nnz  = nzi;
338     k    = lnk[n];
339     while (nnz-- && k < i) {
340       nzbd++;
341       k = lnk[k];
342     }
343     bdiag[i] = nzbd; /* note: bdiag[i] = nnzL as input for PetscFreeSpaceContiguous_LU() */
344 
345     /* if free space is not available, make more free space */
346     if (current_space->local_remaining<nzi) {
347       /* estimated additional space needed */
348       nnz  = PetscIntMultTruncate(2,PetscIntMultTruncate(n-1,nzi));
349       ierr = PetscFreeSpaceGet(nnz,&current_space);CHKERRQ(ierr);
350       reallocs++;
351     }
352 
353     /* copy data into free space, then initialize lnk */
354     ierr = PetscLLClean(n,n,nzi,lnk,current_space->array,lnkbt);CHKERRQ(ierr);
355 
356     bi_ptr[i]                       = current_space->array;
357     current_space->array           += nzi;
358     current_space->local_used      += nzi;
359     current_space->local_remaining -= nzi;
360   }
361 
362   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
363   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
364 
365   /*   copy free_space into bj and free free_space; set bi, bj, bdiag in new datastructure; */
366   ierr = PetscMalloc1(bi[n]+1,&bj);CHKERRQ(ierr);
367   ierr = PetscFreeSpaceContiguous_LU(&free_space,bj,n,bi,bdiag);CHKERRQ(ierr);
368   ierr = PetscLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
369   ierr = PetscFree2(bi_ptr,im);CHKERRQ(ierr);
370 
371   /* put together the new matrix */
372   ierr = MatSeqAIJSetPreallocation_SeqAIJ(B,MAT_SKIP_ALLOCATION,NULL);CHKERRQ(ierr);
373   ierr = PetscLogObjectParent((PetscObject)B,(PetscObject)isicol);CHKERRQ(ierr);
374   b    = (Mat_SeqAIJ*)(B)->data;
375 
376   b->free_a       = PETSC_TRUE;
377   b->free_ij      = PETSC_TRUE;
378   b->singlemalloc = PETSC_FALSE;
379 
380   ierr = PetscMalloc1(bdiag[0]+1,&b->a);CHKERRQ(ierr);
381 
382   b->j    = bj;
383   b->i    = bi;
384   b->diag = bdiag;
385   b->ilen = 0;
386   b->imax = 0;
387   b->row  = isrow;
388   b->col  = iscol;
389   ierr    = PetscObjectReference((PetscObject)isrow);CHKERRQ(ierr);
390   ierr    = PetscObjectReference((PetscObject)iscol);CHKERRQ(ierr);
391   b->icol = isicol;
392   ierr    = PetscMalloc1(n+1,&b->solve_work);CHKERRQ(ierr);
393 
394   /* In b structure:  Free imax, ilen, old a, old j.  Allocate solve_work, new a, new j */
395   ierr     = PetscLogObjectMemory((PetscObject)B,(bdiag[0]+1)*(sizeof(PetscInt)+sizeof(PetscScalar)));CHKERRQ(ierr);
396   b->maxnz = b->nz = bdiag[0]+1;
397 
398   B->factortype            = MAT_FACTOR_LU;
399   B->info.factor_mallocs   = reallocs;
400   B->info.fill_ratio_given = f;
401 
402   if (ai[n]) {
403     B->info.fill_ratio_needed = ((PetscReal)(bdiag[0]+1))/((PetscReal)ai[n]);
404   } else {
405     B->info.fill_ratio_needed = 0.0;
406   }
407 #if defined(PETSC_USE_INFO)
408   if (ai[n] != 0) {
409     PetscReal af = B->info.fill_ratio_needed;
410     ierr = PetscInfo3(A,"Reallocs %D Fill ratio:given %g needed %g\n",reallocs,(double)f,(double)af);CHKERRQ(ierr);
411     ierr = PetscInfo1(A,"Run with -pc_factor_fill %g or use \n",(double)af);CHKERRQ(ierr);
412     ierr = PetscInfo1(A,"PCFactorSetFill(pc,%g);\n",(double)af);CHKERRQ(ierr);
413     ierr = PetscInfo(A,"for best performance.\n");CHKERRQ(ierr);
414   } else {
415     ierr = PetscInfo(A,"Empty matrix\n");CHKERRQ(ierr);
416   }
417 #endif
418   B->ops->lufactornumeric = MatLUFactorNumeric_SeqAIJ;
419   if (a->inode.size) {
420     B->ops->lufactornumeric = MatLUFactorNumeric_SeqAIJ_Inode;
421   }
422   ierr = MatSeqAIJCheckInode_FactorLU(B);CHKERRQ(ierr);
423   PetscFunctionReturn(0);
424 }
425 
426 /*
427     Trouble in factorization, should we dump the original matrix?
428 */
429 PetscErrorCode MatFactorDumpMatrix(Mat A)
430 {
431   PetscErrorCode ierr;
432   PetscBool      flg = PETSC_FALSE;
433 
434   PetscFunctionBegin;
435   ierr = PetscOptionsGetBool(((PetscObject)A)->options,NULL,"-mat_factor_dump_on_error",&flg,NULL);CHKERRQ(ierr);
436   if (flg) {
437     PetscViewer viewer;
438     char        filename[PETSC_MAX_PATH_LEN];
439 
440     ierr = PetscSNPrintf(filename,PETSC_MAX_PATH_LEN,"matrix_factor_error.%d",PetscGlobalRank);CHKERRQ(ierr);
441     ierr = PetscViewerBinaryOpen(PetscObjectComm((PetscObject)A),filename,FILE_MODE_WRITE,&viewer);CHKERRQ(ierr);
442     ierr = MatView(A,viewer);CHKERRQ(ierr);
443     ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
444   }
445   PetscFunctionReturn(0);
446 }
447 
448 PetscErrorCode MatLUFactorNumeric_SeqAIJ(Mat B,Mat A,const MatFactorInfo *info)
449 {
450   Mat             C     =B;
451   Mat_SeqAIJ      *a    =(Mat_SeqAIJ*)A->data,*b=(Mat_SeqAIJ*)C->data;
452   IS              isrow = b->row,isicol = b->icol;
453   PetscErrorCode  ierr;
454   const PetscInt  *r,*ic,*ics;
455   const PetscInt  n=A->rmap->n,*ai=a->i,*aj=a->j,*bi=b->i,*bj=b->j,*bdiag=b->diag;
456   PetscInt        i,j,k,nz,nzL,row,*pj;
457   const PetscInt  *ajtmp,*bjtmp;
458   MatScalar       *rtmp,*pc,multiplier,*pv;
459   const MatScalar *aa=a->a,*v;
460   PetscBool       row_identity,col_identity;
461   FactorShiftCtx  sctx;
462   const PetscInt  *ddiag;
463   PetscReal       rs;
464   MatScalar       d;
465 
466   PetscFunctionBegin;
467   /* MatPivotSetUp(): initialize shift context sctx */
468   ierr = PetscMemzero(&sctx,sizeof(FactorShiftCtx));CHKERRQ(ierr);
469 
470   if (info->shifttype == (PetscReal) MAT_SHIFT_POSITIVE_DEFINITE) { /* set sctx.shift_top=max{rs} */
471     ddiag          = a->diag;
472     sctx.shift_top = info->zeropivot;
473     for (i=0; i<n; i++) {
474       /* calculate sum(|aij|)-RealPart(aii), amt of shift needed for this row */
475       d  = (aa)[ddiag[i]];
476       rs = -PetscAbsScalar(d) - PetscRealPart(d);
477       v  = aa+ai[i];
478       nz = ai[i+1] - ai[i];
479       for (j=0; j<nz; j++) rs += PetscAbsScalar(v[j]);
480       if (rs>sctx.shift_top) sctx.shift_top = rs;
481     }
482     sctx.shift_top *= 1.1;
483     sctx.nshift_max = 5;
484     sctx.shift_lo   = 0.;
485     sctx.shift_hi   = 1.;
486   }
487 
488   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
489   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
490   ierr = PetscMalloc1(n+1,&rtmp);CHKERRQ(ierr);
491   ics  = ic;
492 
493   do {
494     sctx.newshift = PETSC_FALSE;
495     for (i=0; i<n; i++) {
496       /* zero rtmp */
497       /* L part */
498       nz    = bi[i+1] - bi[i];
499       bjtmp = bj + bi[i];
500       for  (j=0; j<nz; j++) rtmp[bjtmp[j]] = 0.0;
501 
502       /* U part */
503       nz    = bdiag[i]-bdiag[i+1];
504       bjtmp = bj + bdiag[i+1]+1;
505       for  (j=0; j<nz; j++) rtmp[bjtmp[j]] = 0.0;
506 
507       /* load in initial (unfactored row) */
508       nz    = ai[r[i]+1] - ai[r[i]];
509       ajtmp = aj + ai[r[i]];
510       v     = aa + ai[r[i]];
511       for (j=0; j<nz; j++) {
512         rtmp[ics[ajtmp[j]]] = v[j];
513       }
514       /* ZeropivotApply() */
515       rtmp[i] += sctx.shift_amount;  /* shift the diagonal of the matrix */
516 
517       /* elimination */
518       bjtmp = bj + bi[i];
519       row   = *bjtmp++;
520       nzL   = bi[i+1] - bi[i];
521       for (k=0; k < nzL; k++) {
522         pc = rtmp + row;
523         if (*pc != 0.0) {
524           pv         = b->a + bdiag[row];
525           multiplier = *pc * (*pv);
526           *pc        = multiplier;
527 
528           pj = b->j + bdiag[row+1]+1; /* beginning of U(row,:) */
529           pv = b->a + bdiag[row+1]+1;
530           nz = bdiag[row]-bdiag[row+1]-1; /* num of entries in U(row,:) excluding diag */
531 
532           for (j=0; j<nz; j++) rtmp[pj[j]] -= multiplier * pv[j];
533           ierr = PetscLogFlops(1+2*nz);CHKERRQ(ierr);
534         }
535         row = *bjtmp++;
536       }
537 
538       /* finished row so stick it into b->a */
539       rs = 0.0;
540       /* L part */
541       pv = b->a + bi[i];
542       pj = b->j + bi[i];
543       nz = bi[i+1] - bi[i];
544       for (j=0; j<nz; j++) {
545         pv[j] = rtmp[pj[j]]; rs += PetscAbsScalar(pv[j]);
546       }
547 
548       /* U part */
549       pv = b->a + bdiag[i+1]+1;
550       pj = b->j + bdiag[i+1]+1;
551       nz = bdiag[i] - bdiag[i+1]-1;
552       for (j=0; j<nz; j++) {
553         pv[j] = rtmp[pj[j]]; rs += PetscAbsScalar(pv[j]);
554       }
555 
556       sctx.rs = rs;
557       sctx.pv = rtmp[i];
558       ierr    = MatPivotCheck(B,A,info,&sctx,i);CHKERRQ(ierr);
559       if (sctx.newshift) break; /* break for-loop */
560       rtmp[i] = sctx.pv; /* sctx.pv might be updated in the case of MAT_SHIFT_INBLOCKS */
561 
562       /* Mark diagonal and invert diagonal for simplier triangular solves */
563       pv  = b->a + bdiag[i];
564       *pv = 1.0/rtmp[i];
565 
566     } /* endof for (i=0; i<n; i++) { */
567 
568     /* MatPivotRefine() */
569     if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE && !sctx.newshift && sctx.shift_fraction>0 && sctx.nshift<sctx.nshift_max) {
570       /*
571        * if no shift in this attempt & shifting & started shifting & can refine,
572        * then try lower shift
573        */
574       sctx.shift_hi       = sctx.shift_fraction;
575       sctx.shift_fraction = (sctx.shift_hi+sctx.shift_lo)/2.;
576       sctx.shift_amount   = sctx.shift_fraction * sctx.shift_top;
577       sctx.newshift       = PETSC_TRUE;
578       sctx.nshift++;
579     }
580   } while (sctx.newshift);
581 
582   ierr = PetscFree(rtmp);CHKERRQ(ierr);
583   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
584   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
585 
586   ierr = ISIdentity(isrow,&row_identity);CHKERRQ(ierr);
587   ierr = ISIdentity(isicol,&col_identity);CHKERRQ(ierr);
588   if (b->inode.size) {
589     C->ops->solve = MatSolve_SeqAIJ_Inode;
590   } else if (row_identity && col_identity) {
591     C->ops->solve = MatSolve_SeqAIJ_NaturalOrdering;
592   } else {
593     C->ops->solve = MatSolve_SeqAIJ;
594   }
595   C->ops->solveadd          = MatSolveAdd_SeqAIJ;
596   C->ops->solvetranspose    = MatSolveTranspose_SeqAIJ;
597   C->ops->solvetransposeadd = MatSolveTransposeAdd_SeqAIJ;
598   C->ops->matsolve          = MatMatSolve_SeqAIJ;
599   C->assembled              = PETSC_TRUE;
600   C->preallocated           = PETSC_TRUE;
601 
602   ierr = PetscLogFlops(C->cmap->n);CHKERRQ(ierr);
603 
604   /* MatShiftView(A,info,&sctx) */
605   if (sctx.nshift) {
606     if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE) {
607       ierr = PetscInfo4(A,"number of shift_pd tries %D, shift_amount %g, diagonal shifted up by %e fraction top_value %e\n",sctx.nshift,(double)sctx.shift_amount,(double)sctx.shift_fraction,(double)sctx.shift_top);CHKERRQ(ierr);
608     } else if (info->shifttype == (PetscReal)MAT_SHIFT_NONZERO) {
609       ierr = PetscInfo2(A,"number of shift_nz tries %D, shift_amount %g\n",sctx.nshift,(double)sctx.shift_amount);CHKERRQ(ierr);
610     } else if (info->shifttype == (PetscReal)MAT_SHIFT_INBLOCKS) {
611       ierr = PetscInfo2(A,"number of shift_inblocks applied %D, each shift_amount %g\n",sctx.nshift,(double)info->shiftamount);CHKERRQ(ierr);
612     }
613   }
614   PetscFunctionReturn(0);
615 }
616 
617 PetscErrorCode MatLUFactorNumeric_SeqAIJ_inplace(Mat B,Mat A,const MatFactorInfo *info)
618 {
619   Mat             C     =B;
620   Mat_SeqAIJ      *a    =(Mat_SeqAIJ*)A->data,*b=(Mat_SeqAIJ*)C->data;
621   IS              isrow = b->row,isicol = b->icol;
622   PetscErrorCode  ierr;
623   const PetscInt  *r,*ic,*ics;
624   PetscInt        nz,row,i,j,n=A->rmap->n,diag;
625   const PetscInt  *ai=a->i,*aj=a->j,*bi=b->i,*bj=b->j;
626   const PetscInt  *ajtmp,*bjtmp,*diag_offset = b->diag,*pj;
627   MatScalar       *pv,*rtmp,*pc,multiplier,d;
628   const MatScalar *v,*aa=a->a;
629   PetscReal       rs=0.0;
630   FactorShiftCtx  sctx;
631   const PetscInt  *ddiag;
632   PetscBool       row_identity, col_identity;
633 
634   PetscFunctionBegin;
635   /* MatPivotSetUp(): initialize shift context sctx */
636   ierr = PetscMemzero(&sctx,sizeof(FactorShiftCtx));CHKERRQ(ierr);
637 
638   if (info->shifttype == (PetscReal) MAT_SHIFT_POSITIVE_DEFINITE) { /* set sctx.shift_top=max{rs} */
639     ddiag          = a->diag;
640     sctx.shift_top = info->zeropivot;
641     for (i=0; i<n; i++) {
642       /* calculate sum(|aij|)-RealPart(aii), amt of shift needed for this row */
643       d  = (aa)[ddiag[i]];
644       rs = -PetscAbsScalar(d) - PetscRealPart(d);
645       v  = aa+ai[i];
646       nz = ai[i+1] - ai[i];
647       for (j=0; j<nz; j++) rs += PetscAbsScalar(v[j]);
648       if (rs>sctx.shift_top) sctx.shift_top = rs;
649     }
650     sctx.shift_top *= 1.1;
651     sctx.nshift_max = 5;
652     sctx.shift_lo   = 0.;
653     sctx.shift_hi   = 1.;
654   }
655 
656   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
657   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
658   ierr = PetscMalloc1(n+1,&rtmp);CHKERRQ(ierr);
659   ics  = ic;
660 
661   do {
662     sctx.newshift = PETSC_FALSE;
663     for (i=0; i<n; i++) {
664       nz    = bi[i+1] - bi[i];
665       bjtmp = bj + bi[i];
666       for  (j=0; j<nz; j++) rtmp[bjtmp[j]] = 0.0;
667 
668       /* load in initial (unfactored row) */
669       nz    = ai[r[i]+1] - ai[r[i]];
670       ajtmp = aj + ai[r[i]];
671       v     = aa + ai[r[i]];
672       for (j=0; j<nz; j++) {
673         rtmp[ics[ajtmp[j]]] = v[j];
674       }
675       rtmp[ics[r[i]]] += sctx.shift_amount; /* shift the diagonal of the matrix */
676 
677       row = *bjtmp++;
678       while  (row < i) {
679         pc = rtmp + row;
680         if (*pc != 0.0) {
681           pv         = b->a + diag_offset[row];
682           pj         = b->j + diag_offset[row] + 1;
683           multiplier = *pc / *pv++;
684           *pc        = multiplier;
685           nz         = bi[row+1] - diag_offset[row] - 1;
686           for (j=0; j<nz; j++) rtmp[pj[j]] -= multiplier * pv[j];
687           ierr = PetscLogFlops(1+2*nz);CHKERRQ(ierr);
688         }
689         row = *bjtmp++;
690       }
691       /* finished row so stick it into b->a */
692       pv   = b->a + bi[i];
693       pj   = b->j + bi[i];
694       nz   = bi[i+1] - bi[i];
695       diag = diag_offset[i] - bi[i];
696       rs   = 0.0;
697       for (j=0; j<nz; j++) {
698         pv[j] = rtmp[pj[j]];
699         rs   += PetscAbsScalar(pv[j]);
700       }
701       rs -= PetscAbsScalar(pv[diag]);
702 
703       sctx.rs = rs;
704       sctx.pv = pv[diag];
705       ierr    = MatPivotCheck(B,A,info,&sctx,i);CHKERRQ(ierr);
706       if (sctx.newshift) break;
707       pv[diag] = sctx.pv;
708     }
709 
710     if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE && !sctx.newshift && sctx.shift_fraction>0 && sctx.nshift<sctx.nshift_max) {
711       /*
712        * if no shift in this attempt & shifting & started shifting & can refine,
713        * then try lower shift
714        */
715       sctx.shift_hi       = sctx.shift_fraction;
716       sctx.shift_fraction = (sctx.shift_hi+sctx.shift_lo)/2.;
717       sctx.shift_amount   = sctx.shift_fraction * sctx.shift_top;
718       sctx.newshift       = PETSC_TRUE;
719       sctx.nshift++;
720     }
721   } while (sctx.newshift);
722 
723   /* invert diagonal entries for simplier triangular solves */
724   for (i=0; i<n; i++) {
725     b->a[diag_offset[i]] = 1.0/b->a[diag_offset[i]];
726   }
727   ierr = PetscFree(rtmp);CHKERRQ(ierr);
728   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
729   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
730 
731   ierr = ISIdentity(isrow,&row_identity);CHKERRQ(ierr);
732   ierr = ISIdentity(isicol,&col_identity);CHKERRQ(ierr);
733   if (row_identity && col_identity) {
734     C->ops->solve = MatSolve_SeqAIJ_NaturalOrdering_inplace;
735   } else {
736     C->ops->solve = MatSolve_SeqAIJ_inplace;
737   }
738   C->ops->solveadd          = MatSolveAdd_SeqAIJ_inplace;
739   C->ops->solvetranspose    = MatSolveTranspose_SeqAIJ_inplace;
740   C->ops->solvetransposeadd = MatSolveTransposeAdd_SeqAIJ_inplace;
741   C->ops->matsolve          = MatMatSolve_SeqAIJ_inplace;
742 
743   C->assembled    = PETSC_TRUE;
744   C->preallocated = PETSC_TRUE;
745 
746   ierr = PetscLogFlops(C->cmap->n);CHKERRQ(ierr);
747   if (sctx.nshift) {
748     if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE) {
749       ierr = PetscInfo4(A,"number of shift_pd tries %D, shift_amount %g, diagonal shifted up by %e fraction top_value %e\n",sctx.nshift,(double)sctx.shift_amount,(double)sctx.shift_fraction,(double)sctx.shift_top);CHKERRQ(ierr);
750     } else if (info->shifttype == (PetscReal)MAT_SHIFT_NONZERO) {
751       ierr = PetscInfo2(A,"number of shift_nz tries %D, shift_amount %g\n",sctx.nshift,(double)sctx.shift_amount);CHKERRQ(ierr);
752     }
753   }
754   (C)->ops->solve          = MatSolve_SeqAIJ_inplace;
755   (C)->ops->solvetranspose = MatSolveTranspose_SeqAIJ_inplace;
756 
757   ierr = MatSeqAIJCheckInode(C);CHKERRQ(ierr);
758   PetscFunctionReturn(0);
759 }
760 
761 /*
762    This routine implements inplace ILU(0) with row or/and column permutations.
763    Input:
764      A - original matrix
765    Output;
766      A - a->i (rowptr) is same as original rowptr, but factored i-the row is stored in rowperm[i]
767          a->j (col index) is permuted by the inverse of colperm, then sorted
768          a->a reordered accordingly with a->j
769          a->diag (ptr to diagonal elements) is updated.
770 */
771 PetscErrorCode MatLUFactorNumeric_SeqAIJ_InplaceWithPerm(Mat B,Mat A,const MatFactorInfo *info)
772 {
773   Mat_SeqAIJ      *a    =(Mat_SeqAIJ*)A->data;
774   IS              isrow = a->row,isicol = a->icol;
775   PetscErrorCode  ierr;
776   const PetscInt  *r,*ic,*ics;
777   PetscInt        i,j,n=A->rmap->n,*ai=a->i,*aj=a->j;
778   PetscInt        *ajtmp,nz,row;
779   PetscInt        *diag = a->diag,nbdiag,*pj;
780   PetscScalar     *rtmp,*pc,multiplier,d;
781   MatScalar       *pv,*v;
782   PetscReal       rs;
783   FactorShiftCtx  sctx;
784   const MatScalar *aa=a->a,*vtmp;
785 
786   PetscFunctionBegin;
787   if (A != B) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_INCOMP,"input and output matrix must have same address");
788 
789   /* MatPivotSetUp(): initialize shift context sctx */
790   ierr = PetscMemzero(&sctx,sizeof(FactorShiftCtx));CHKERRQ(ierr);
791 
792   if (info->shifttype == (PetscReal) MAT_SHIFT_POSITIVE_DEFINITE) { /* set sctx.shift_top=max{rs} */
793     const PetscInt *ddiag = a->diag;
794     sctx.shift_top = info->zeropivot;
795     for (i=0; i<n; i++) {
796       /* calculate sum(|aij|)-RealPart(aii), amt of shift needed for this row */
797       d    = (aa)[ddiag[i]];
798       rs   = -PetscAbsScalar(d) - PetscRealPart(d);
799       vtmp = aa+ai[i];
800       nz   = ai[i+1] - ai[i];
801       for (j=0; j<nz; j++) rs += PetscAbsScalar(vtmp[j]);
802       if (rs>sctx.shift_top) sctx.shift_top = rs;
803     }
804     sctx.shift_top *= 1.1;
805     sctx.nshift_max = 5;
806     sctx.shift_lo   = 0.;
807     sctx.shift_hi   = 1.;
808   }
809 
810   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
811   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
812   ierr = PetscMalloc1(n+1,&rtmp);CHKERRQ(ierr);
813   ierr = PetscMemzero(rtmp,(n+1)*sizeof(PetscScalar));CHKERRQ(ierr);
814   ics  = ic;
815 
816 #if defined(MV)
817   sctx.shift_top      = 0.;
818   sctx.nshift_max     = 0;
819   sctx.shift_lo       = 0.;
820   sctx.shift_hi       = 0.;
821   sctx.shift_fraction = 0.;
822 
823   if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE) { /* set sctx.shift_top=max{rs} */
824     sctx.shift_top = 0.;
825     for (i=0; i<n; i++) {
826       /* calculate sum(|aij|)-RealPart(aii), amt of shift needed for this row */
827       d  = (a->a)[diag[i]];
828       rs = -PetscAbsScalar(d) - PetscRealPart(d);
829       v  = a->a+ai[i];
830       nz = ai[i+1] - ai[i];
831       for (j=0; j<nz; j++) rs += PetscAbsScalar(v[j]);
832       if (rs>sctx.shift_top) sctx.shift_top = rs;
833     }
834     if (sctx.shift_top < info->zeropivot) sctx.shift_top = info->zeropivot;
835     sctx.shift_top *= 1.1;
836     sctx.nshift_max = 5;
837     sctx.shift_lo   = 0.;
838     sctx.shift_hi   = 1.;
839   }
840 
841   sctx.shift_amount = 0.;
842   sctx.nshift       = 0;
843 #endif
844 
845   do {
846     sctx.newshift = PETSC_FALSE;
847     for (i=0; i<n; i++) {
848       /* load in initial unfactored row */
849       nz    = ai[r[i]+1] - ai[r[i]];
850       ajtmp = aj + ai[r[i]];
851       v     = a->a + ai[r[i]];
852       /* sort permuted ajtmp and values v accordingly */
853       for (j=0; j<nz; j++) ajtmp[j] = ics[ajtmp[j]];
854       ierr = PetscSortIntWithScalarArray(nz,ajtmp,v);CHKERRQ(ierr);
855 
856       diag[r[i]] = ai[r[i]];
857       for (j=0; j<nz; j++) {
858         rtmp[ajtmp[j]] = v[j];
859         if (ajtmp[j] < i) diag[r[i]]++; /* update a->diag */
860       }
861       rtmp[r[i]] += sctx.shift_amount; /* shift the diagonal of the matrix */
862 
863       row = *ajtmp++;
864       while  (row < i) {
865         pc = rtmp + row;
866         if (*pc != 0.0) {
867           pv = a->a + diag[r[row]];
868           pj = aj + diag[r[row]] + 1;
869 
870           multiplier = *pc / *pv++;
871           *pc        = multiplier;
872           nz         = ai[r[row]+1] - diag[r[row]] - 1;
873           for (j=0; j<nz; j++) rtmp[pj[j]] -= multiplier * pv[j];
874           ierr = PetscLogFlops(1+2*nz);CHKERRQ(ierr);
875         }
876         row = *ajtmp++;
877       }
878       /* finished row so overwrite it onto a->a */
879       pv     = a->a + ai[r[i]];
880       pj     = aj + ai[r[i]];
881       nz     = ai[r[i]+1] - ai[r[i]];
882       nbdiag = diag[r[i]] - ai[r[i]]; /* num of entries before the diagonal */
883 
884       rs = 0.0;
885       for (j=0; j<nz; j++) {
886         pv[j] = rtmp[pj[j]];
887         if (j != nbdiag) rs += PetscAbsScalar(pv[j]);
888       }
889 
890       sctx.rs = rs;
891       sctx.pv = pv[nbdiag];
892       ierr    = MatPivotCheck(B,A,info,&sctx,i);CHKERRQ(ierr);
893       if (sctx.newshift) break;
894       pv[nbdiag] = sctx.pv;
895     }
896 
897     if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE && !sctx.newshift && sctx.shift_fraction>0 && sctx.nshift<sctx.nshift_max) {
898       /*
899        * if no shift in this attempt & shifting & started shifting & can refine,
900        * then try lower shift
901        */
902       sctx.shift_hi       = sctx.shift_fraction;
903       sctx.shift_fraction = (sctx.shift_hi+sctx.shift_lo)/2.;
904       sctx.shift_amount   = sctx.shift_fraction * sctx.shift_top;
905       sctx.newshift       = PETSC_TRUE;
906       sctx.nshift++;
907     }
908   } while (sctx.newshift);
909 
910   /* invert diagonal entries for simplier triangular solves */
911   for (i=0; i<n; i++) {
912     a->a[diag[r[i]]] = 1.0/a->a[diag[r[i]]];
913   }
914 
915   ierr = PetscFree(rtmp);CHKERRQ(ierr);
916   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
917   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
918 
919   A->ops->solve             = MatSolve_SeqAIJ_InplaceWithPerm;
920   A->ops->solveadd          = MatSolveAdd_SeqAIJ_inplace;
921   A->ops->solvetranspose    = MatSolveTranspose_SeqAIJ_inplace;
922   A->ops->solvetransposeadd = MatSolveTransposeAdd_SeqAIJ_inplace;
923 
924   A->assembled    = PETSC_TRUE;
925   A->preallocated = PETSC_TRUE;
926 
927   ierr = PetscLogFlops(A->cmap->n);CHKERRQ(ierr);
928   if (sctx.nshift) {
929     if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE) {
930       ierr = PetscInfo4(A,"number of shift_pd tries %D, shift_amount %g, diagonal shifted up by %e fraction top_value %e\n",sctx.nshift,(double)sctx.shift_amount,(double)sctx.shift_fraction,(double)sctx.shift_top);CHKERRQ(ierr);
931     } else if (info->shifttype == (PetscReal)MAT_SHIFT_NONZERO) {
932       ierr = PetscInfo2(A,"number of shift_nz tries %D, shift_amount %g\n",sctx.nshift,(double)sctx.shift_amount);CHKERRQ(ierr);
933     }
934   }
935   PetscFunctionReturn(0);
936 }
937 
938 /* ----------------------------------------------------------- */
939 PetscErrorCode MatLUFactor_SeqAIJ(Mat A,IS row,IS col,const MatFactorInfo *info)
940 {
941   PetscErrorCode ierr;
942   Mat            C;
943 
944   PetscFunctionBegin;
945   ierr = MatGetFactor(A,MATSOLVERPETSC,MAT_FACTOR_LU,&C);CHKERRQ(ierr);
946   ierr = MatLUFactorSymbolic(C,A,row,col,info);CHKERRQ(ierr);
947   ierr = MatLUFactorNumeric(C,A,info);CHKERRQ(ierr);
948 
949   A->ops->solve          = C->ops->solve;
950   A->ops->solvetranspose = C->ops->solvetranspose;
951 
952   ierr = MatHeaderMerge(A,&C);CHKERRQ(ierr);
953   ierr = PetscLogObjectParent((PetscObject)A,(PetscObject)((Mat_SeqAIJ*)(A->data))->icol);CHKERRQ(ierr);
954   PetscFunctionReturn(0);
955 }
956 /* ----------------------------------------------------------- */
957 
958 
959 PetscErrorCode MatSolve_SeqAIJ_inplace(Mat A,Vec bb,Vec xx)
960 {
961   Mat_SeqAIJ        *a    = (Mat_SeqAIJ*)A->data;
962   IS                iscol = a->col,isrow = a->row;
963   PetscErrorCode    ierr;
964   PetscInt          i, n = A->rmap->n,*vi,*ai = a->i,*aj = a->j;
965   PetscInt          nz;
966   const PetscInt    *rout,*cout,*r,*c;
967   PetscScalar       *x,*tmp,*tmps,sum;
968   const PetscScalar *b;
969   const MatScalar   *aa = a->a,*v;
970 
971   PetscFunctionBegin;
972   if (!n) PetscFunctionReturn(0);
973 
974   ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr);
975   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
976   tmp  = a->solve_work;
977 
978   ierr = ISGetIndices(isrow,&rout);CHKERRQ(ierr); r = rout;
979   ierr = ISGetIndices(iscol,&cout);CHKERRQ(ierr); c = cout + (n-1);
980 
981   /* forward solve the lower triangular */
982   tmp[0] = b[*r++];
983   tmps   = tmp;
984   for (i=1; i<n; i++) {
985     v   = aa + ai[i];
986     vi  = aj + ai[i];
987     nz  = a->diag[i] - ai[i];
988     sum = b[*r++];
989     PetscSparseDenseMinusDot(sum,tmps,v,vi,nz);
990     tmp[i] = sum;
991   }
992 
993   /* backward solve the upper triangular */
994   for (i=n-1; i>=0; i--) {
995     v   = aa + a->diag[i] + 1;
996     vi  = aj + a->diag[i] + 1;
997     nz  = ai[i+1] - a->diag[i] - 1;
998     sum = tmp[i];
999     PetscSparseDenseMinusDot(sum,tmps,v,vi,nz);
1000     x[*c--] = tmp[i] = sum*aa[a->diag[i]];
1001   }
1002 
1003   ierr = ISRestoreIndices(isrow,&rout);CHKERRQ(ierr);
1004   ierr = ISRestoreIndices(iscol,&cout);CHKERRQ(ierr);
1005   ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr);
1006   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
1007   ierr = PetscLogFlops(2.0*a->nz - A->cmap->n);CHKERRQ(ierr);
1008   PetscFunctionReturn(0);
1009 }
1010 
1011 PetscErrorCode MatMatSolve_SeqAIJ_inplace(Mat A,Mat B,Mat X)
1012 {
1013   Mat_SeqAIJ      *a    = (Mat_SeqAIJ*)A->data;
1014   IS              iscol = a->col,isrow = a->row;
1015   PetscErrorCode  ierr;
1016   PetscInt        i, n = A->rmap->n,*vi,*ai = a->i,*aj = a->j;
1017   PetscInt        nz,neq;
1018   const PetscInt  *rout,*cout,*r,*c;
1019   PetscScalar     *x,*b,*tmp,*tmps,sum;
1020   const MatScalar *aa = a->a,*v;
1021   PetscBool       bisdense,xisdense;
1022 
1023   PetscFunctionBegin;
1024   if (!n) PetscFunctionReturn(0);
1025 
1026   ierr = PetscObjectTypeCompare((PetscObject)B,MATSEQDENSE,&bisdense);CHKERRQ(ierr);
1027   if (!bisdense) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_INCOMP,"B matrix must be a SeqDense matrix");
1028   ierr = PetscObjectTypeCompare((PetscObject)X,MATSEQDENSE,&xisdense);CHKERRQ(ierr);
1029   if (!xisdense) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_INCOMP,"X matrix must be a SeqDense matrix");
1030 
1031   ierr = MatDenseGetArray(B,&b);CHKERRQ(ierr);
1032   ierr = MatDenseGetArray(X,&x);CHKERRQ(ierr);
1033 
1034   tmp  = a->solve_work;
1035   ierr = ISGetIndices(isrow,&rout);CHKERRQ(ierr); r = rout;
1036   ierr = ISGetIndices(iscol,&cout);CHKERRQ(ierr); c = cout;
1037 
1038   for (neq=0; neq<B->cmap->n; neq++) {
1039     /* forward solve the lower triangular */
1040     tmp[0] = b[r[0]];
1041     tmps   = tmp;
1042     for (i=1; i<n; i++) {
1043       v   = aa + ai[i];
1044       vi  = aj + ai[i];
1045       nz  = a->diag[i] - ai[i];
1046       sum = b[r[i]];
1047       PetscSparseDenseMinusDot(sum,tmps,v,vi,nz);
1048       tmp[i] = sum;
1049     }
1050     /* backward solve the upper triangular */
1051     for (i=n-1; i>=0; i--) {
1052       v   = aa + a->diag[i] + 1;
1053       vi  = aj + a->diag[i] + 1;
1054       nz  = ai[i+1] - a->diag[i] - 1;
1055       sum = tmp[i];
1056       PetscSparseDenseMinusDot(sum,tmps,v,vi,nz);
1057       x[c[i]] = tmp[i] = sum*aa[a->diag[i]];
1058     }
1059 
1060     b += n;
1061     x += n;
1062   }
1063   ierr = ISRestoreIndices(isrow,&rout);CHKERRQ(ierr);
1064   ierr = ISRestoreIndices(iscol,&cout);CHKERRQ(ierr);
1065   ierr = MatDenseRestoreArray(B,&b);CHKERRQ(ierr);
1066   ierr = MatDenseRestoreArray(X,&x);CHKERRQ(ierr);
1067   ierr = PetscLogFlops(B->cmap->n*(2.0*a->nz - n));CHKERRQ(ierr);
1068   PetscFunctionReturn(0);
1069 }
1070 
1071 PetscErrorCode MatMatSolve_SeqAIJ(Mat A,Mat B,Mat X)
1072 {
1073   Mat_SeqAIJ      *a    = (Mat_SeqAIJ*)A->data;
1074   IS              iscol = a->col,isrow = a->row;
1075   PetscErrorCode  ierr;
1076   PetscInt        i, n = A->rmap->n,*vi,*ai = a->i,*aj = a->j,*adiag = a->diag;
1077   PetscInt        nz,neq;
1078   const PetscInt  *rout,*cout,*r,*c;
1079   PetscScalar     *x,*b,*tmp,sum;
1080   const MatScalar *aa = a->a,*v;
1081   PetscBool       bisdense,xisdense;
1082 
1083   PetscFunctionBegin;
1084   if (!n) PetscFunctionReturn(0);
1085 
1086   ierr = PetscObjectTypeCompare((PetscObject)B,MATSEQDENSE,&bisdense);CHKERRQ(ierr);
1087   if (!bisdense) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_INCOMP,"B matrix must be a SeqDense matrix");
1088   ierr = PetscObjectTypeCompare((PetscObject)X,MATSEQDENSE,&xisdense);CHKERRQ(ierr);
1089   if (!xisdense) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_INCOMP,"X matrix must be a SeqDense matrix");
1090 
1091   ierr = MatDenseGetArray(B,&b);CHKERRQ(ierr);
1092   ierr = MatDenseGetArray(X,&x);CHKERRQ(ierr);
1093 
1094   tmp  = a->solve_work;
1095   ierr = ISGetIndices(isrow,&rout);CHKERRQ(ierr); r = rout;
1096   ierr = ISGetIndices(iscol,&cout);CHKERRQ(ierr); c = cout;
1097 
1098   for (neq=0; neq<B->cmap->n; neq++) {
1099     /* forward solve the lower triangular */
1100     tmp[0] = b[r[0]];
1101     v      = aa;
1102     vi     = aj;
1103     for (i=1; i<n; i++) {
1104       nz  = ai[i+1] - ai[i];
1105       sum = b[r[i]];
1106       PetscSparseDenseMinusDot(sum,tmp,v,vi,nz);
1107       tmp[i] = sum;
1108       v     += nz; vi += nz;
1109     }
1110 
1111     /* backward solve the upper triangular */
1112     for (i=n-1; i>=0; i--) {
1113       v   = aa + adiag[i+1]+1;
1114       vi  = aj + adiag[i+1]+1;
1115       nz  = adiag[i]-adiag[i+1]-1;
1116       sum = tmp[i];
1117       PetscSparseDenseMinusDot(sum,tmp,v,vi,nz);
1118       x[c[i]] = tmp[i] = sum*v[nz]; /* v[nz] = aa[adiag[i]] */
1119     }
1120 
1121     b += n;
1122     x += n;
1123   }
1124   ierr = ISRestoreIndices(isrow,&rout);CHKERRQ(ierr);
1125   ierr = ISRestoreIndices(iscol,&cout);CHKERRQ(ierr);
1126   ierr = MatDenseRestoreArray(B,&b);CHKERRQ(ierr);
1127   ierr = MatDenseRestoreArray(X,&x);CHKERRQ(ierr);
1128   ierr = PetscLogFlops(B->cmap->n*(2.0*a->nz - n));CHKERRQ(ierr);
1129   PetscFunctionReturn(0);
1130 }
1131 
1132 PetscErrorCode MatSolve_SeqAIJ_InplaceWithPerm(Mat A,Vec bb,Vec xx)
1133 {
1134   Mat_SeqAIJ      *a    = (Mat_SeqAIJ*)A->data;
1135   IS              iscol = a->col,isrow = a->row;
1136   PetscErrorCode  ierr;
1137   const PetscInt  *r,*c,*rout,*cout;
1138   PetscInt        i, n = A->rmap->n,*vi,*ai = a->i,*aj = a->j;
1139   PetscInt        nz,row;
1140   PetscScalar     *x,*b,*tmp,*tmps,sum;
1141   const MatScalar *aa = a->a,*v;
1142 
1143   PetscFunctionBegin;
1144   if (!n) PetscFunctionReturn(0);
1145 
1146   ierr = VecGetArray(bb,&b);CHKERRQ(ierr);
1147   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
1148   tmp  = a->solve_work;
1149 
1150   ierr = ISGetIndices(isrow,&rout);CHKERRQ(ierr); r = rout;
1151   ierr = ISGetIndices(iscol,&cout);CHKERRQ(ierr); c = cout + (n-1);
1152 
1153   /* forward solve the lower triangular */
1154   tmp[0] = b[*r++];
1155   tmps   = tmp;
1156   for (row=1; row<n; row++) {
1157     i   = rout[row]; /* permuted row */
1158     v   = aa + ai[i];
1159     vi  = aj + ai[i];
1160     nz  = a->diag[i] - ai[i];
1161     sum = b[*r++];
1162     PetscSparseDenseMinusDot(sum,tmps,v,vi,nz);
1163     tmp[row] = sum;
1164   }
1165 
1166   /* backward solve the upper triangular */
1167   for (row=n-1; row>=0; row--) {
1168     i   = rout[row]; /* permuted row */
1169     v   = aa + a->diag[i] + 1;
1170     vi  = aj + a->diag[i] + 1;
1171     nz  = ai[i+1] - a->diag[i] - 1;
1172     sum = tmp[row];
1173     PetscSparseDenseMinusDot(sum,tmps,v,vi,nz);
1174     x[*c--] = tmp[row] = sum*aa[a->diag[i]];
1175   }
1176 
1177   ierr = ISRestoreIndices(isrow,&rout);CHKERRQ(ierr);
1178   ierr = ISRestoreIndices(iscol,&cout);CHKERRQ(ierr);
1179   ierr = VecRestoreArray(bb,&b);CHKERRQ(ierr);
1180   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
1181   ierr = PetscLogFlops(2.0*a->nz - A->cmap->n);CHKERRQ(ierr);
1182   PetscFunctionReturn(0);
1183 }
1184 
1185 /* ----------------------------------------------------------- */
1186 #include <../src/mat/impls/aij/seq/ftn-kernels/fsolve.h>
1187 PetscErrorCode MatSolve_SeqAIJ_NaturalOrdering_inplace(Mat A,Vec bb,Vec xx)
1188 {
1189   Mat_SeqAIJ        *a = (Mat_SeqAIJ*)A->data;
1190   PetscErrorCode    ierr;
1191   PetscInt          n   = A->rmap->n;
1192   const PetscInt    *ai = a->i,*aj = a->j,*adiag = a->diag;
1193   PetscScalar       *x;
1194   const PetscScalar *b;
1195   const MatScalar   *aa = a->a;
1196 #if !defined(PETSC_USE_FORTRAN_KERNEL_SOLVEAIJ)
1197   PetscInt        adiag_i,i,nz,ai_i;
1198   const PetscInt  *vi;
1199   const MatScalar *v;
1200   PetscScalar     sum;
1201 #endif
1202 
1203   PetscFunctionBegin;
1204   if (!n) PetscFunctionReturn(0);
1205 
1206   ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr);
1207   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
1208 
1209 #if defined(PETSC_USE_FORTRAN_KERNEL_SOLVEAIJ)
1210   fortransolveaij_(&n,x,ai,aj,adiag,aa,b);
1211 #else
1212   /* forward solve the lower triangular */
1213   x[0] = b[0];
1214   for (i=1; i<n; i++) {
1215     ai_i = ai[i];
1216     v    = aa + ai_i;
1217     vi   = aj + ai_i;
1218     nz   = adiag[i] - ai_i;
1219     sum  = b[i];
1220     PetscSparseDenseMinusDot(sum,x,v,vi,nz);
1221     x[i] = sum;
1222   }
1223 
1224   /* backward solve the upper triangular */
1225   for (i=n-1; i>=0; i--) {
1226     adiag_i = adiag[i];
1227     v       = aa + adiag_i + 1;
1228     vi      = aj + adiag_i + 1;
1229     nz      = ai[i+1] - adiag_i - 1;
1230     sum     = x[i];
1231     PetscSparseDenseMinusDot(sum,x,v,vi,nz);
1232     x[i] = sum*aa[adiag_i];
1233   }
1234 #endif
1235   ierr = PetscLogFlops(2.0*a->nz - A->cmap->n);CHKERRQ(ierr);
1236   ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr);
1237   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
1238   PetscFunctionReturn(0);
1239 }
1240 
1241 PetscErrorCode MatSolveAdd_SeqAIJ_inplace(Mat A,Vec bb,Vec yy,Vec xx)
1242 {
1243   Mat_SeqAIJ        *a    = (Mat_SeqAIJ*)A->data;
1244   IS                iscol = a->col,isrow = a->row;
1245   PetscErrorCode    ierr;
1246   PetscInt          i, n = A->rmap->n,j;
1247   PetscInt          nz;
1248   const PetscInt    *rout,*cout,*r,*c,*vi,*ai = a->i,*aj = a->j;
1249   PetscScalar       *x,*tmp,sum;
1250   const PetscScalar *b;
1251   const MatScalar   *aa = a->a,*v;
1252 
1253   PetscFunctionBegin;
1254   if (yy != xx) {ierr = VecCopy(yy,xx);CHKERRQ(ierr);}
1255 
1256   ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr);
1257   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
1258   tmp  = a->solve_work;
1259 
1260   ierr = ISGetIndices(isrow,&rout);CHKERRQ(ierr); r = rout;
1261   ierr = ISGetIndices(iscol,&cout);CHKERRQ(ierr); c = cout + (n-1);
1262 
1263   /* forward solve the lower triangular */
1264   tmp[0] = b[*r++];
1265   for (i=1; i<n; i++) {
1266     v   = aa + ai[i];
1267     vi  = aj + ai[i];
1268     nz  = a->diag[i] - ai[i];
1269     sum = b[*r++];
1270     for (j=0; j<nz; j++) sum -= v[j]*tmp[vi[j]];
1271     tmp[i] = sum;
1272   }
1273 
1274   /* backward solve the upper triangular */
1275   for (i=n-1; i>=0; i--) {
1276     v   = aa + a->diag[i] + 1;
1277     vi  = aj + a->diag[i] + 1;
1278     nz  = ai[i+1] - a->diag[i] - 1;
1279     sum = tmp[i];
1280     for (j=0; j<nz; j++) sum -= v[j]*tmp[vi[j]];
1281     tmp[i]   = sum*aa[a->diag[i]];
1282     x[*c--] += tmp[i];
1283   }
1284 
1285   ierr = ISRestoreIndices(isrow,&rout);CHKERRQ(ierr);
1286   ierr = ISRestoreIndices(iscol,&cout);CHKERRQ(ierr);
1287   ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr);
1288   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
1289   ierr = PetscLogFlops(2.0*a->nz);CHKERRQ(ierr);
1290   PetscFunctionReturn(0);
1291 }
1292 
1293 PetscErrorCode MatSolveAdd_SeqAIJ(Mat A,Vec bb,Vec yy,Vec xx)
1294 {
1295   Mat_SeqAIJ        *a    = (Mat_SeqAIJ*)A->data;
1296   IS                iscol = a->col,isrow = a->row;
1297   PetscErrorCode    ierr;
1298   PetscInt          i, n = A->rmap->n,j;
1299   PetscInt          nz;
1300   const PetscInt    *rout,*cout,*r,*c,*vi,*ai = a->i,*aj = a->j,*adiag = a->diag;
1301   PetscScalar       *x,*tmp,sum;
1302   const PetscScalar *b;
1303   const MatScalar   *aa = a->a,*v;
1304 
1305   PetscFunctionBegin;
1306   if (yy != xx) {ierr = VecCopy(yy,xx);CHKERRQ(ierr);}
1307 
1308   ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr);
1309   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
1310   tmp  = a->solve_work;
1311 
1312   ierr = ISGetIndices(isrow,&rout);CHKERRQ(ierr); r = rout;
1313   ierr = ISGetIndices(iscol,&cout);CHKERRQ(ierr); c = cout;
1314 
1315   /* forward solve the lower triangular */
1316   tmp[0] = b[r[0]];
1317   v      = aa;
1318   vi     = aj;
1319   for (i=1; i<n; i++) {
1320     nz  = ai[i+1] - ai[i];
1321     sum = b[r[i]];
1322     for (j=0; j<nz; j++) sum -= v[j]*tmp[vi[j]];
1323     tmp[i] = sum;
1324     v     += nz;
1325     vi    += nz;
1326   }
1327 
1328   /* backward solve the upper triangular */
1329   v  = aa + adiag[n-1];
1330   vi = aj + adiag[n-1];
1331   for (i=n-1; i>=0; i--) {
1332     nz  = adiag[i] - adiag[i+1] - 1;
1333     sum = tmp[i];
1334     for (j=0; j<nz; j++) sum -= v[j]*tmp[vi[j]];
1335     tmp[i]   = sum*v[nz];
1336     x[c[i]] += tmp[i];
1337     v       += nz+1; vi += nz+1;
1338   }
1339 
1340   ierr = ISRestoreIndices(isrow,&rout);CHKERRQ(ierr);
1341   ierr = ISRestoreIndices(iscol,&cout);CHKERRQ(ierr);
1342   ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr);
1343   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
1344   ierr = PetscLogFlops(2.0*a->nz);CHKERRQ(ierr);
1345   PetscFunctionReturn(0);
1346 }
1347 
1348 PetscErrorCode MatSolveTranspose_SeqAIJ_inplace(Mat A,Vec bb,Vec xx)
1349 {
1350   Mat_SeqAIJ        *a    = (Mat_SeqAIJ*)A->data;
1351   IS                iscol = a->col,isrow = a->row;
1352   PetscErrorCode    ierr;
1353   const PetscInt    *rout,*cout,*r,*c,*diag = a->diag,*ai = a->i,*aj = a->j,*vi;
1354   PetscInt          i,n = A->rmap->n,j;
1355   PetscInt          nz;
1356   PetscScalar       *x,*tmp,s1;
1357   const MatScalar   *aa = a->a,*v;
1358   const PetscScalar *b;
1359 
1360   PetscFunctionBegin;
1361   ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr);
1362   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
1363   tmp  = a->solve_work;
1364 
1365   ierr = ISGetIndices(isrow,&rout);CHKERRQ(ierr); r = rout;
1366   ierr = ISGetIndices(iscol,&cout);CHKERRQ(ierr); c = cout;
1367 
1368   /* copy the b into temp work space according to permutation */
1369   for (i=0; i<n; i++) tmp[i] = b[c[i]];
1370 
1371   /* forward solve the U^T */
1372   for (i=0; i<n; i++) {
1373     v   = aa + diag[i];
1374     vi  = aj + diag[i] + 1;
1375     nz  = ai[i+1] - diag[i] - 1;
1376     s1  = tmp[i];
1377     s1 *= (*v++);  /* multiply by inverse of diagonal entry */
1378     for (j=0; j<nz; j++) tmp[vi[j]] -= s1*v[j];
1379     tmp[i] = s1;
1380   }
1381 
1382   /* backward solve the L^T */
1383   for (i=n-1; i>=0; i--) {
1384     v  = aa + diag[i] - 1;
1385     vi = aj + diag[i] - 1;
1386     nz = diag[i] - ai[i];
1387     s1 = tmp[i];
1388     for (j=0; j>-nz; j--) tmp[vi[j]] -= s1*v[j];
1389   }
1390 
1391   /* copy tmp into x according to permutation */
1392   for (i=0; i<n; i++) x[r[i]] = tmp[i];
1393 
1394   ierr = ISRestoreIndices(isrow,&rout);CHKERRQ(ierr);
1395   ierr = ISRestoreIndices(iscol,&cout);CHKERRQ(ierr);
1396   ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr);
1397   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
1398 
1399   ierr = PetscLogFlops(2.0*a->nz-A->cmap->n);CHKERRQ(ierr);
1400   PetscFunctionReturn(0);
1401 }
1402 
1403 PetscErrorCode MatSolveTranspose_SeqAIJ(Mat A,Vec bb,Vec xx)
1404 {
1405   Mat_SeqAIJ        *a    = (Mat_SeqAIJ*)A->data;
1406   IS                iscol = a->col,isrow = a->row;
1407   PetscErrorCode    ierr;
1408   const PetscInt    *rout,*cout,*r,*c,*adiag = a->diag,*ai = a->i,*aj = a->j,*vi;
1409   PetscInt          i,n = A->rmap->n,j;
1410   PetscInt          nz;
1411   PetscScalar       *x,*tmp,s1;
1412   const MatScalar   *aa = a->a,*v;
1413   const PetscScalar *b;
1414 
1415   PetscFunctionBegin;
1416   ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr);
1417   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
1418   tmp  = a->solve_work;
1419 
1420   ierr = ISGetIndices(isrow,&rout);CHKERRQ(ierr); r = rout;
1421   ierr = ISGetIndices(iscol,&cout);CHKERRQ(ierr); c = cout;
1422 
1423   /* copy the b into temp work space according to permutation */
1424   for (i=0; i<n; i++) tmp[i] = b[c[i]];
1425 
1426   /* forward solve the U^T */
1427   for (i=0; i<n; i++) {
1428     v   = aa + adiag[i+1] + 1;
1429     vi  = aj + adiag[i+1] + 1;
1430     nz  = adiag[i] - adiag[i+1] - 1;
1431     s1  = tmp[i];
1432     s1 *= v[nz];  /* multiply by inverse of diagonal entry */
1433     for (j=0; j<nz; j++) tmp[vi[j]] -= s1*v[j];
1434     tmp[i] = s1;
1435   }
1436 
1437   /* backward solve the L^T */
1438   for (i=n-1; i>=0; i--) {
1439     v  = aa + ai[i];
1440     vi = aj + ai[i];
1441     nz = ai[i+1] - ai[i];
1442     s1 = tmp[i];
1443     for (j=0; j<nz; j++) tmp[vi[j]] -= s1*v[j];
1444   }
1445 
1446   /* copy tmp into x according to permutation */
1447   for (i=0; i<n; i++) x[r[i]] = tmp[i];
1448 
1449   ierr = ISRestoreIndices(isrow,&rout);CHKERRQ(ierr);
1450   ierr = ISRestoreIndices(iscol,&cout);CHKERRQ(ierr);
1451   ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr);
1452   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
1453 
1454   ierr = PetscLogFlops(2.0*a->nz-A->cmap->n);CHKERRQ(ierr);
1455   PetscFunctionReturn(0);
1456 }
1457 
1458 PetscErrorCode MatSolveTransposeAdd_SeqAIJ_inplace(Mat A,Vec bb,Vec zz,Vec xx)
1459 {
1460   Mat_SeqAIJ        *a    = (Mat_SeqAIJ*)A->data;
1461   IS                iscol = a->col,isrow = a->row;
1462   PetscErrorCode    ierr;
1463   const PetscInt    *rout,*cout,*r,*c,*diag = a->diag,*ai = a->i,*aj = a->j,*vi;
1464   PetscInt          i,n = A->rmap->n,j;
1465   PetscInt          nz;
1466   PetscScalar       *x,*tmp,s1;
1467   const MatScalar   *aa = a->a,*v;
1468   const PetscScalar *b;
1469 
1470   PetscFunctionBegin;
1471   if (zz != xx) {ierr = VecCopy(zz,xx);CHKERRQ(ierr);}
1472   ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr);
1473   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
1474   tmp  = a->solve_work;
1475 
1476   ierr = ISGetIndices(isrow,&rout);CHKERRQ(ierr); r = rout;
1477   ierr = ISGetIndices(iscol,&cout);CHKERRQ(ierr); c = cout;
1478 
1479   /* copy the b into temp work space according to permutation */
1480   for (i=0; i<n; i++) tmp[i] = b[c[i]];
1481 
1482   /* forward solve the U^T */
1483   for (i=0; i<n; i++) {
1484     v   = aa + diag[i];
1485     vi  = aj + diag[i] + 1;
1486     nz  = ai[i+1] - diag[i] - 1;
1487     s1  = tmp[i];
1488     s1 *= (*v++);  /* multiply by inverse of diagonal entry */
1489     for (j=0; j<nz; j++) tmp[vi[j]] -= s1*v[j];
1490     tmp[i] = s1;
1491   }
1492 
1493   /* backward solve the L^T */
1494   for (i=n-1; i>=0; i--) {
1495     v  = aa + diag[i] - 1;
1496     vi = aj + diag[i] - 1;
1497     nz = diag[i] - ai[i];
1498     s1 = tmp[i];
1499     for (j=0; j>-nz; j--) tmp[vi[j]] -= s1*v[j];
1500   }
1501 
1502   /* copy tmp into x according to permutation */
1503   for (i=0; i<n; i++) x[r[i]] += tmp[i];
1504 
1505   ierr = ISRestoreIndices(isrow,&rout);CHKERRQ(ierr);
1506   ierr = ISRestoreIndices(iscol,&cout);CHKERRQ(ierr);
1507   ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr);
1508   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
1509 
1510   ierr = PetscLogFlops(2.0*a->nz-A->cmap->n);CHKERRQ(ierr);
1511   PetscFunctionReturn(0);
1512 }
1513 
1514 PetscErrorCode MatSolveTransposeAdd_SeqAIJ(Mat A,Vec bb,Vec zz,Vec xx)
1515 {
1516   Mat_SeqAIJ        *a    = (Mat_SeqAIJ*)A->data;
1517   IS                iscol = a->col,isrow = a->row;
1518   PetscErrorCode    ierr;
1519   const PetscInt    *rout,*cout,*r,*c,*adiag = a->diag,*ai = a->i,*aj = a->j,*vi;
1520   PetscInt          i,n = A->rmap->n,j;
1521   PetscInt          nz;
1522   PetscScalar       *x,*tmp,s1;
1523   const MatScalar   *aa = a->a,*v;
1524   const PetscScalar *b;
1525 
1526   PetscFunctionBegin;
1527   if (zz != xx) {ierr = VecCopy(zz,xx);CHKERRQ(ierr);}
1528   ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr);
1529   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
1530   tmp  = a->solve_work;
1531 
1532   ierr = ISGetIndices(isrow,&rout);CHKERRQ(ierr); r = rout;
1533   ierr = ISGetIndices(iscol,&cout);CHKERRQ(ierr); c = cout;
1534 
1535   /* copy the b into temp work space according to permutation */
1536   for (i=0; i<n; i++) tmp[i] = b[c[i]];
1537 
1538   /* forward solve the U^T */
1539   for (i=0; i<n; i++) {
1540     v   = aa + adiag[i+1] + 1;
1541     vi  = aj + adiag[i+1] + 1;
1542     nz  = adiag[i] - adiag[i+1] - 1;
1543     s1  = tmp[i];
1544     s1 *= v[nz];  /* multiply by inverse of diagonal entry */
1545     for (j=0; j<nz; j++) tmp[vi[j]] -= s1*v[j];
1546     tmp[i] = s1;
1547   }
1548 
1549 
1550   /* backward solve the L^T */
1551   for (i=n-1; i>=0; i--) {
1552     v  = aa + ai[i];
1553     vi = aj + ai[i];
1554     nz = ai[i+1] - ai[i];
1555     s1 = tmp[i];
1556     for (j=0; j<nz; j++) tmp[vi[j]] -= s1*v[j];
1557   }
1558 
1559   /* copy tmp into x according to permutation */
1560   for (i=0; i<n; i++) x[r[i]] += tmp[i];
1561 
1562   ierr = ISRestoreIndices(isrow,&rout);CHKERRQ(ierr);
1563   ierr = ISRestoreIndices(iscol,&cout);CHKERRQ(ierr);
1564   ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr);
1565   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
1566 
1567   ierr = PetscLogFlops(2.0*a->nz-A->cmap->n);CHKERRQ(ierr);
1568   PetscFunctionReturn(0);
1569 }
1570 
1571 /* ----------------------------------------------------------------*/
1572 
1573 extern PetscErrorCode MatDuplicateNoCreate_SeqAIJ(Mat,Mat,MatDuplicateOption,PetscBool);
1574 
1575 /*
1576    ilu() under revised new data structure.
1577    Factored arrays bj and ba are stored as
1578      L(0,:), L(1,:), ...,L(n-1,:),  U(n-1,:),...,U(i,:),U(i-1,:),...,U(0,:)
1579 
1580    bi=fact->i is an array of size n+1, in which
1581    bi+
1582      bi[i]:  points to 1st entry of L(i,:),i=0,...,n-1
1583      bi[n]:  points to L(n-1,n-1)+1
1584 
1585   bdiag=fact->diag is an array of size n+1,in which
1586      bdiag[i]: points to diagonal of U(i,:), i=0,...,n-1
1587      bdiag[n]: points to entry of U(n-1,0)-1
1588 
1589    U(i,:) contains bdiag[i] as its last entry, i.e.,
1590     U(i,:) = (u[i,i+1],...,u[i,n-1],diag[i])
1591 */
1592 PetscErrorCode MatILUFactorSymbolic_SeqAIJ_ilu0(Mat fact,Mat A,IS isrow,IS iscol,const MatFactorInfo *info)
1593 {
1594   Mat_SeqAIJ     *a = (Mat_SeqAIJ*)A->data,*b;
1595   PetscErrorCode ierr;
1596   const PetscInt n=A->rmap->n,*ai=a->i,*aj,*adiag=a->diag;
1597   PetscInt       i,j,k=0,nz,*bi,*bj,*bdiag;
1598   IS             isicol;
1599 
1600   PetscFunctionBegin;
1601   ierr = ISInvertPermutation(iscol,PETSC_DECIDE,&isicol);CHKERRQ(ierr);
1602   ierr = MatDuplicateNoCreate_SeqAIJ(fact,A,MAT_DO_NOT_COPY_VALUES,PETSC_FALSE);CHKERRQ(ierr);
1603   b    = (Mat_SeqAIJ*)(fact)->data;
1604 
1605   /* allocate matrix arrays for new data structure */
1606   ierr = PetscMalloc3(ai[n]+1,&b->a,ai[n]+1,&b->j,n+1,&b->i);CHKERRQ(ierr);
1607   ierr = PetscLogObjectMemory((PetscObject)fact,ai[n]*(sizeof(PetscScalar)+sizeof(PetscInt))+(n+1)*sizeof(PetscInt));CHKERRQ(ierr);
1608 
1609   b->singlemalloc = PETSC_TRUE;
1610   if (!b->diag) {
1611     ierr = PetscMalloc1(n+1,&b->diag);CHKERRQ(ierr);
1612     ierr = PetscLogObjectMemory((PetscObject)fact,(n+1)*sizeof(PetscInt));CHKERRQ(ierr);
1613   }
1614   bdiag = b->diag;
1615 
1616   if (n > 0) {
1617     ierr = PetscMemzero(b->a,(ai[n])*sizeof(MatScalar));CHKERRQ(ierr);
1618   }
1619 
1620   /* set bi and bj with new data structure */
1621   bi = b->i;
1622   bj = b->j;
1623 
1624   /* L part */
1625   bi[0] = 0;
1626   for (i=0; i<n; i++) {
1627     nz      = adiag[i] - ai[i];
1628     bi[i+1] = bi[i] + nz;
1629     aj      = a->j + ai[i];
1630     for (j=0; j<nz; j++) {
1631       /*   *bj = aj[j]; bj++; */
1632       bj[k++] = aj[j];
1633     }
1634   }
1635 
1636   /* U part */
1637   bdiag[n] = bi[n]-1;
1638   for (i=n-1; i>=0; i--) {
1639     nz = ai[i+1] - adiag[i] - 1;
1640     aj = a->j + adiag[i] + 1;
1641     for (j=0; j<nz; j++) {
1642       /*      *bj = aj[j]; bj++; */
1643       bj[k++] = aj[j];
1644     }
1645     /* diag[i] */
1646     /*    *bj = i; bj++; */
1647     bj[k++]  = i;
1648     bdiag[i] = bdiag[i+1] + nz + 1;
1649   }
1650 
1651   fact->factortype             = MAT_FACTOR_ILU;
1652   fact->info.factor_mallocs    = 0;
1653   fact->info.fill_ratio_given  = info->fill;
1654   fact->info.fill_ratio_needed = 1.0;
1655   fact->ops->lufactornumeric   = MatLUFactorNumeric_SeqAIJ;
1656   ierr = MatSeqAIJCheckInode_FactorLU(fact);CHKERRQ(ierr);
1657 
1658   b       = (Mat_SeqAIJ*)(fact)->data;
1659   b->row  = isrow;
1660   b->col  = iscol;
1661   b->icol = isicol;
1662   ierr    = PetscMalloc1(fact->rmap->n+1,&b->solve_work);CHKERRQ(ierr);
1663   ierr    = PetscObjectReference((PetscObject)isrow);CHKERRQ(ierr);
1664   ierr    = PetscObjectReference((PetscObject)iscol);CHKERRQ(ierr);
1665   PetscFunctionReturn(0);
1666 }
1667 
1668 PetscErrorCode MatILUFactorSymbolic_SeqAIJ(Mat fact,Mat A,IS isrow,IS iscol,const MatFactorInfo *info)
1669 {
1670   Mat_SeqAIJ         *a = (Mat_SeqAIJ*)A->data,*b;
1671   IS                 isicol;
1672   PetscErrorCode     ierr;
1673   const PetscInt     *r,*ic;
1674   PetscInt           n=A->rmap->n,*ai=a->i,*aj=a->j;
1675   PetscInt           *bi,*cols,nnz,*cols_lvl;
1676   PetscInt           *bdiag,prow,fm,nzbd,reallocs=0,dcount=0;
1677   PetscInt           i,levels,diagonal_fill;
1678   PetscBool          col_identity,row_identity,missing;
1679   PetscReal          f;
1680   PetscInt           nlnk,*lnk,*lnk_lvl=NULL;
1681   PetscBT            lnkbt;
1682   PetscInt           nzi,*bj,**bj_ptr,**bjlvl_ptr;
1683   PetscFreeSpaceList free_space    =NULL,current_space=NULL;
1684   PetscFreeSpaceList free_space_lvl=NULL,current_space_lvl=NULL;
1685 
1686   PetscFunctionBegin;
1687   if (A->rmap->n != A->cmap->n) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Must be square matrix, rows %D columns %D",A->rmap->n,A->cmap->n);
1688   ierr = MatMissingDiagonal(A,&missing,&i);CHKERRQ(ierr);
1689   if (missing) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Matrix is missing diagonal entry %D",i);
1690 
1691   levels = (PetscInt)info->levels;
1692   ierr   = ISIdentity(isrow,&row_identity);CHKERRQ(ierr);
1693   ierr   = ISIdentity(iscol,&col_identity);CHKERRQ(ierr);
1694   if (!levels && row_identity && col_identity) {
1695     /* special case: ilu(0) with natural ordering */
1696     ierr = MatILUFactorSymbolic_SeqAIJ_ilu0(fact,A,isrow,iscol,info);CHKERRQ(ierr);
1697     if (a->inode.size) {
1698       fact->ops->lufactornumeric = MatLUFactorNumeric_SeqAIJ_Inode;
1699     }
1700     PetscFunctionReturn(0);
1701   }
1702 
1703   ierr = ISInvertPermutation(iscol,PETSC_DECIDE,&isicol);CHKERRQ(ierr);
1704   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
1705   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
1706 
1707   /* get new row and diagonal pointers, must be allocated separately because they will be given to the Mat_SeqAIJ and freed separately */
1708   ierr  = PetscMalloc1(n+1,&bi);CHKERRQ(ierr);
1709   ierr  = PetscMalloc1(n+1,&bdiag);CHKERRQ(ierr);
1710   bi[0] = bdiag[0] = 0;
1711   ierr  = PetscMalloc2(n,&bj_ptr,n,&bjlvl_ptr);CHKERRQ(ierr);
1712 
1713   /* create a linked list for storing column indices of the active row */
1714   nlnk = n + 1;
1715   ierr = PetscIncompleteLLCreate(n,n,nlnk,lnk,lnk_lvl,lnkbt);CHKERRQ(ierr);
1716 
1717   /* initial FreeSpace size is f*(ai[n]+1) */
1718   f                 = info->fill;
1719   diagonal_fill     = (PetscInt)info->diagonal_fill;
1720   ierr              = PetscFreeSpaceGet(PetscRealIntMultTruncate(f,ai[n]+1),&free_space);CHKERRQ(ierr);
1721   current_space     = free_space;
1722   ierr              = PetscFreeSpaceGet(PetscRealIntMultTruncate(f,ai[n]+1),&free_space_lvl);CHKERRQ(ierr);
1723   current_space_lvl = free_space_lvl;
1724   for (i=0; i<n; i++) {
1725     nzi = 0;
1726     /* copy current row into linked list */
1727     nnz = ai[r[i]+1] - ai[r[i]];
1728     if (!nnz) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_MAT_LU_ZRPVT,"Empty row in matrix: row in original ordering %D in permuted ordering %D",r[i],i);
1729     cols   = aj + ai[r[i]];
1730     lnk[i] = -1; /* marker to indicate if diagonal exists */
1731     ierr   = PetscIncompleteLLInit(nnz,cols,n,ic,nlnk,lnk,lnk_lvl,lnkbt);CHKERRQ(ierr);
1732     nzi   += nlnk;
1733 
1734     /* make sure diagonal entry is included */
1735     if (diagonal_fill && lnk[i] == -1) {
1736       fm = n;
1737       while (lnk[fm] < i) fm = lnk[fm];
1738       lnk[i]     = lnk[fm]; /* insert diagonal into linked list */
1739       lnk[fm]    = i;
1740       lnk_lvl[i] = 0;
1741       nzi++; dcount++;
1742     }
1743 
1744     /* add pivot rows into the active row */
1745     nzbd = 0;
1746     prow = lnk[n];
1747     while (prow < i) {
1748       nnz      = bdiag[prow];
1749       cols     = bj_ptr[prow] + nnz + 1;
1750       cols_lvl = bjlvl_ptr[prow] + nnz + 1;
1751       nnz      = bi[prow+1] - bi[prow] - nnz - 1;
1752       ierr     = PetscILULLAddSorted(nnz,cols,levels,cols_lvl,prow,nlnk,lnk,lnk_lvl,lnkbt,prow);CHKERRQ(ierr);
1753       nzi     += nlnk;
1754       prow     = lnk[prow];
1755       nzbd++;
1756     }
1757     bdiag[i] = nzbd;
1758     bi[i+1]  = bi[i] + nzi;
1759     /* if free space is not available, make more free space */
1760     if (current_space->local_remaining<nzi) {
1761       nnz  = PetscIntMultTruncate(2,PetscIntMultTruncate(nzi,n - i)); /* estimated and max additional space needed */
1762       ierr = PetscFreeSpaceGet(nnz,&current_space);CHKERRQ(ierr);
1763       ierr = PetscFreeSpaceGet(nnz,&current_space_lvl);CHKERRQ(ierr);
1764       reallocs++;
1765     }
1766 
1767     /* copy data into free_space and free_space_lvl, then initialize lnk */
1768     ierr         = PetscIncompleteLLClean(n,n,nzi,lnk,lnk_lvl,current_space->array,current_space_lvl->array,lnkbt);CHKERRQ(ierr);
1769     bj_ptr[i]    = current_space->array;
1770     bjlvl_ptr[i] = current_space_lvl->array;
1771 
1772     /* make sure the active row i has diagonal entry */
1773     if (*(bj_ptr[i]+bdiag[i]) != i) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_MAT_LU_ZRPVT,"Row %D has missing diagonal in factored matrix\ntry running with -pc_factor_nonzeros_along_diagonal or -pc_factor_diagonal_fill",i);
1774 
1775     current_space->array               += nzi;
1776     current_space->local_used          += nzi;
1777     current_space->local_remaining     -= nzi;
1778     current_space_lvl->array           += nzi;
1779     current_space_lvl->local_used      += nzi;
1780     current_space_lvl->local_remaining -= nzi;
1781   }
1782 
1783   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
1784   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
1785   /* copy free_space into bj and free free_space; set bi, bj, bdiag in new datastructure; */
1786   ierr = PetscMalloc1(bi[n]+1,&bj);CHKERRQ(ierr);
1787   ierr = PetscFreeSpaceContiguous_LU(&free_space,bj,n,bi,bdiag);CHKERRQ(ierr);
1788 
1789   ierr = PetscIncompleteLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
1790   ierr = PetscFreeSpaceDestroy(free_space_lvl);CHKERRQ(ierr);
1791   ierr = PetscFree2(bj_ptr,bjlvl_ptr);CHKERRQ(ierr);
1792 
1793 #if defined(PETSC_USE_INFO)
1794   {
1795     PetscReal af = ((PetscReal)(bdiag[0]+1))/((PetscReal)ai[n]);
1796     ierr = PetscInfo3(A,"Reallocs %D Fill ratio:given %g needed %g\n",reallocs,(double)f,(double)af);CHKERRQ(ierr);
1797     ierr = PetscInfo1(A,"Run with -[sub_]pc_factor_fill %g or use \n",(double)af);CHKERRQ(ierr);
1798     ierr = PetscInfo1(A,"PCFactorSetFill([sub]pc,%g);\n",(double)af);CHKERRQ(ierr);
1799     ierr = PetscInfo(A,"for best performance.\n");CHKERRQ(ierr);
1800     if (diagonal_fill) {
1801       ierr = PetscInfo1(A,"Detected and replaced %D missing diagonals\n",dcount);CHKERRQ(ierr);
1802     }
1803   }
1804 #endif
1805   /* put together the new matrix */
1806   ierr = MatSeqAIJSetPreallocation_SeqAIJ(fact,MAT_SKIP_ALLOCATION,NULL);CHKERRQ(ierr);
1807   ierr = PetscLogObjectParent((PetscObject)fact,(PetscObject)isicol);CHKERRQ(ierr);
1808   b    = (Mat_SeqAIJ*)(fact)->data;
1809 
1810   b->free_a       = PETSC_TRUE;
1811   b->free_ij      = PETSC_TRUE;
1812   b->singlemalloc = PETSC_FALSE;
1813 
1814   ierr = PetscMalloc1(bdiag[0]+1,&b->a);CHKERRQ(ierr);
1815 
1816   b->j    = bj;
1817   b->i    = bi;
1818   b->diag = bdiag;
1819   b->ilen = 0;
1820   b->imax = 0;
1821   b->row  = isrow;
1822   b->col  = iscol;
1823   ierr    = PetscObjectReference((PetscObject)isrow);CHKERRQ(ierr);
1824   ierr    = PetscObjectReference((PetscObject)iscol);CHKERRQ(ierr);
1825   b->icol = isicol;
1826 
1827   ierr = PetscMalloc1(n+1,&b->solve_work);CHKERRQ(ierr);
1828   /* In b structure:  Free imax, ilen, old a, old j.
1829      Allocate bdiag, solve_work, new a, new j */
1830   ierr     = PetscLogObjectMemory((PetscObject)fact,(bdiag[0]+1)*(sizeof(PetscInt)+sizeof(PetscScalar)));CHKERRQ(ierr);
1831   b->maxnz = b->nz = bdiag[0]+1;
1832 
1833   (fact)->info.factor_mallocs    = reallocs;
1834   (fact)->info.fill_ratio_given  = f;
1835   (fact)->info.fill_ratio_needed = ((PetscReal)(bdiag[0]+1))/((PetscReal)ai[n]);
1836   (fact)->ops->lufactornumeric   = MatLUFactorNumeric_SeqAIJ;
1837   if (a->inode.size) {
1838     (fact)->ops->lufactornumeric = MatLUFactorNumeric_SeqAIJ_Inode;
1839   }
1840   ierr = MatSeqAIJCheckInode_FactorLU(fact);CHKERRQ(ierr);
1841   PetscFunctionReturn(0);
1842 }
1843 
1844 PetscErrorCode MatILUFactorSymbolic_SeqAIJ_inplace(Mat fact,Mat A,IS isrow,IS iscol,const MatFactorInfo *info)
1845 {
1846   Mat_SeqAIJ         *a = (Mat_SeqAIJ*)A->data,*b;
1847   IS                 isicol;
1848   PetscErrorCode     ierr;
1849   const PetscInt     *r,*ic;
1850   PetscInt           n=A->rmap->n,*ai=a->i,*aj=a->j;
1851   PetscInt           *bi,*cols,nnz,*cols_lvl;
1852   PetscInt           *bdiag,prow,fm,nzbd,reallocs=0,dcount=0;
1853   PetscInt           i,levels,diagonal_fill;
1854   PetscBool          col_identity,row_identity;
1855   PetscReal          f;
1856   PetscInt           nlnk,*lnk,*lnk_lvl=NULL;
1857   PetscBT            lnkbt;
1858   PetscInt           nzi,*bj,**bj_ptr,**bjlvl_ptr;
1859   PetscFreeSpaceList free_space    =NULL,current_space=NULL;
1860   PetscFreeSpaceList free_space_lvl=NULL,current_space_lvl=NULL;
1861   PetscBool          missing;
1862 
1863   PetscFunctionBegin;
1864   if (A->rmap->n != A->cmap->n) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Must be square matrix, rows %D columns %D",A->rmap->n,A->cmap->n);
1865   ierr = MatMissingDiagonal(A,&missing,&i);CHKERRQ(ierr);
1866   if (missing) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Matrix is missing diagonal entry %D",i);
1867 
1868   f             = info->fill;
1869   levels        = (PetscInt)info->levels;
1870   diagonal_fill = (PetscInt)info->diagonal_fill;
1871 
1872   ierr = ISInvertPermutation(iscol,PETSC_DECIDE,&isicol);CHKERRQ(ierr);
1873 
1874   ierr = ISIdentity(isrow,&row_identity);CHKERRQ(ierr);
1875   ierr = ISIdentity(iscol,&col_identity);CHKERRQ(ierr);
1876   if (!levels && row_identity && col_identity) { /* special case: ilu(0) with natural ordering */
1877     ierr = MatDuplicateNoCreate_SeqAIJ(fact,A,MAT_DO_NOT_COPY_VALUES,PETSC_TRUE);CHKERRQ(ierr);
1878 
1879     (fact)->ops->lufactornumeric =  MatLUFactorNumeric_SeqAIJ_inplace;
1880     if (a->inode.size) {
1881       (fact)->ops->lufactornumeric = MatLUFactorNumeric_SeqAIJ_Inode_inplace;
1882     }
1883     fact->factortype               = MAT_FACTOR_ILU;
1884     (fact)->info.factor_mallocs    = 0;
1885     (fact)->info.fill_ratio_given  = info->fill;
1886     (fact)->info.fill_ratio_needed = 1.0;
1887 
1888     b    = (Mat_SeqAIJ*)(fact)->data;
1889     b->row  = isrow;
1890     b->col  = iscol;
1891     b->icol = isicol;
1892     ierr    = PetscMalloc1((fact)->rmap->n+1,&b->solve_work);CHKERRQ(ierr);
1893     ierr    = PetscObjectReference((PetscObject)isrow);CHKERRQ(ierr);
1894     ierr    = PetscObjectReference((PetscObject)iscol);CHKERRQ(ierr);
1895     PetscFunctionReturn(0);
1896   }
1897 
1898   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
1899   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
1900 
1901   /* get new row and diagonal pointers, must be allocated separately because they will be given to the Mat_SeqAIJ and freed separately */
1902   ierr  = PetscMalloc1(n+1,&bi);CHKERRQ(ierr);
1903   ierr  = PetscMalloc1(n+1,&bdiag);CHKERRQ(ierr);
1904   bi[0] = bdiag[0] = 0;
1905 
1906   ierr = PetscMalloc2(n,&bj_ptr,n,&bjlvl_ptr);CHKERRQ(ierr);
1907 
1908   /* create a linked list for storing column indices of the active row */
1909   nlnk = n + 1;
1910   ierr = PetscIncompleteLLCreate(n,n,nlnk,lnk,lnk_lvl,lnkbt);CHKERRQ(ierr);
1911 
1912   /* initial FreeSpace size is f*(ai[n]+1) */
1913   ierr              = PetscFreeSpaceGet(PetscRealIntMultTruncate(f,ai[n]+1),&free_space);CHKERRQ(ierr);
1914   current_space     = free_space;
1915   ierr              = PetscFreeSpaceGet(PetscRealIntMultTruncate(f,ai[n]+1),&free_space_lvl);CHKERRQ(ierr);
1916   current_space_lvl = free_space_lvl;
1917 
1918   for (i=0; i<n; i++) {
1919     nzi = 0;
1920     /* copy current row into linked list */
1921     nnz = ai[r[i]+1] - ai[r[i]];
1922     if (!nnz) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_MAT_LU_ZRPVT,"Empty row in matrix: row in original ordering %D in permuted ordering %D",r[i],i);
1923     cols   = aj + ai[r[i]];
1924     lnk[i] = -1; /* marker to indicate if diagonal exists */
1925     ierr   = PetscIncompleteLLInit(nnz,cols,n,ic,nlnk,lnk,lnk_lvl,lnkbt);CHKERRQ(ierr);
1926     nzi   += nlnk;
1927 
1928     /* make sure diagonal entry is included */
1929     if (diagonal_fill && lnk[i] == -1) {
1930       fm = n;
1931       while (lnk[fm] < i) fm = lnk[fm];
1932       lnk[i]     = lnk[fm]; /* insert diagonal into linked list */
1933       lnk[fm]    = i;
1934       lnk_lvl[i] = 0;
1935       nzi++; dcount++;
1936     }
1937 
1938     /* add pivot rows into the active row */
1939     nzbd = 0;
1940     prow = lnk[n];
1941     while (prow < i) {
1942       nnz      = bdiag[prow];
1943       cols     = bj_ptr[prow] + nnz + 1;
1944       cols_lvl = bjlvl_ptr[prow] + nnz + 1;
1945       nnz      = bi[prow+1] - bi[prow] - nnz - 1;
1946       ierr     = PetscILULLAddSorted(nnz,cols,levels,cols_lvl,prow,nlnk,lnk,lnk_lvl,lnkbt,prow);CHKERRQ(ierr);
1947       nzi     += nlnk;
1948       prow     = lnk[prow];
1949       nzbd++;
1950     }
1951     bdiag[i] = nzbd;
1952     bi[i+1]  = bi[i] + nzi;
1953 
1954     /* if free space is not available, make more free space */
1955     if (current_space->local_remaining<nzi) {
1956       nnz  = PetscIntMultTruncate(nzi,n - i); /* estimated and max additional space needed */
1957       ierr = PetscFreeSpaceGet(nnz,&current_space);CHKERRQ(ierr);
1958       ierr = PetscFreeSpaceGet(nnz,&current_space_lvl);CHKERRQ(ierr);
1959       reallocs++;
1960     }
1961 
1962     /* copy data into free_space and free_space_lvl, then initialize lnk */
1963     ierr         = PetscIncompleteLLClean(n,n,nzi,lnk,lnk_lvl,current_space->array,current_space_lvl->array,lnkbt);CHKERRQ(ierr);
1964     bj_ptr[i]    = current_space->array;
1965     bjlvl_ptr[i] = current_space_lvl->array;
1966 
1967     /* make sure the active row i has diagonal entry */
1968     if (*(bj_ptr[i]+bdiag[i]) != i) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_MAT_LU_ZRPVT,"Row %D has missing diagonal in factored matrix\ntry running with -pc_factor_nonzeros_along_diagonal or -pc_factor_diagonal_fill",i);
1969 
1970     current_space->array               += nzi;
1971     current_space->local_used          += nzi;
1972     current_space->local_remaining     -= nzi;
1973     current_space_lvl->array           += nzi;
1974     current_space_lvl->local_used      += nzi;
1975     current_space_lvl->local_remaining -= nzi;
1976   }
1977 
1978   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
1979   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
1980 
1981   /* destroy list of free space and other temporary arrays */
1982   ierr = PetscMalloc1(bi[n]+1,&bj);CHKERRQ(ierr);
1983   ierr = PetscFreeSpaceContiguous(&free_space,bj);CHKERRQ(ierr); /* copy free_space -> bj */
1984   ierr = PetscIncompleteLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
1985   ierr = PetscFreeSpaceDestroy(free_space_lvl);CHKERRQ(ierr);
1986   ierr = PetscFree2(bj_ptr,bjlvl_ptr);CHKERRQ(ierr);
1987 
1988 #if defined(PETSC_USE_INFO)
1989   {
1990     PetscReal af = ((PetscReal)bi[n])/((PetscReal)ai[n]);
1991     ierr = PetscInfo3(A,"Reallocs %D Fill ratio:given %g needed %g\n",reallocs,(double)f,(double)af);CHKERRQ(ierr);
1992     ierr = PetscInfo1(A,"Run with -[sub_]pc_factor_fill %g or use \n",(double)af);CHKERRQ(ierr);
1993     ierr = PetscInfo1(A,"PCFactorSetFill([sub]pc,%g);\n",(double)af);CHKERRQ(ierr);
1994     ierr = PetscInfo(A,"for best performance.\n");CHKERRQ(ierr);
1995     if (diagonal_fill) {
1996       ierr = PetscInfo1(A,"Detected and replaced %D missing diagonals\n",dcount);CHKERRQ(ierr);
1997     }
1998   }
1999 #endif
2000 
2001   /* put together the new matrix */
2002   ierr = MatSeqAIJSetPreallocation_SeqAIJ(fact,MAT_SKIP_ALLOCATION,NULL);CHKERRQ(ierr);
2003   ierr = PetscLogObjectParent((PetscObject)fact,(PetscObject)isicol);CHKERRQ(ierr);
2004   b    = (Mat_SeqAIJ*)(fact)->data;
2005 
2006   b->free_a       = PETSC_TRUE;
2007   b->free_ij      = PETSC_TRUE;
2008   b->singlemalloc = PETSC_FALSE;
2009 
2010   ierr = PetscMalloc1(bi[n],&b->a);CHKERRQ(ierr);
2011   b->j = bj;
2012   b->i = bi;
2013   for (i=0; i<n; i++) bdiag[i] += bi[i];
2014   b->diag = bdiag;
2015   b->ilen = 0;
2016   b->imax = 0;
2017   b->row  = isrow;
2018   b->col  = iscol;
2019   ierr    = PetscObjectReference((PetscObject)isrow);CHKERRQ(ierr);
2020   ierr    = PetscObjectReference((PetscObject)iscol);CHKERRQ(ierr);
2021   b->icol = isicol;
2022   ierr    = PetscMalloc1(n+1,&b->solve_work);CHKERRQ(ierr);
2023   /* In b structure:  Free imax, ilen, old a, old j.
2024      Allocate bdiag, solve_work, new a, new j */
2025   ierr     = PetscLogObjectMemory((PetscObject)fact,(bi[n]-n) * (sizeof(PetscInt)+sizeof(PetscScalar)));CHKERRQ(ierr);
2026   b->maxnz = b->nz = bi[n];
2027 
2028   (fact)->info.factor_mallocs    = reallocs;
2029   (fact)->info.fill_ratio_given  = f;
2030   (fact)->info.fill_ratio_needed = ((PetscReal)bi[n])/((PetscReal)ai[n]);
2031   (fact)->ops->lufactornumeric   =  MatLUFactorNumeric_SeqAIJ_inplace;
2032   if (a->inode.size) {
2033     (fact)->ops->lufactornumeric = MatLUFactorNumeric_SeqAIJ_Inode_inplace;
2034   }
2035   PetscFunctionReturn(0);
2036 }
2037 
2038 PetscErrorCode MatCholeskyFactorNumeric_SeqAIJ(Mat B,Mat A,const MatFactorInfo *info)
2039 {
2040   Mat            C = B;
2041   Mat_SeqAIJ     *a=(Mat_SeqAIJ*)A->data;
2042   Mat_SeqSBAIJ   *b=(Mat_SeqSBAIJ*)C->data;
2043   IS             ip=b->row,iip = b->icol;
2044   PetscErrorCode ierr;
2045   const PetscInt *rip,*riip;
2046   PetscInt       i,j,mbs=A->rmap->n,*bi=b->i,*bj=b->j,*bdiag=b->diag,*bjtmp;
2047   PetscInt       *ai=a->i,*aj=a->j;
2048   PetscInt       k,jmin,jmax,*c2r,*il,col,nexti,ili,nz;
2049   MatScalar      *rtmp,*ba=b->a,*bval,*aa=a->a,dk,uikdi;
2050   PetscBool      perm_identity;
2051   FactorShiftCtx sctx;
2052   PetscReal      rs;
2053   MatScalar      d,*v;
2054 
2055   PetscFunctionBegin;
2056   /* MatPivotSetUp(): initialize shift context sctx */
2057   ierr = PetscMemzero(&sctx,sizeof(FactorShiftCtx));CHKERRQ(ierr);
2058 
2059   if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE) { /* set sctx.shift_top=max{rs} */
2060     sctx.shift_top = info->zeropivot;
2061     for (i=0; i<mbs; i++) {
2062       /* calculate sum(|aij|)-RealPart(aii), amt of shift needed for this row */
2063       d  = (aa)[a->diag[i]];
2064       rs = -PetscAbsScalar(d) - PetscRealPart(d);
2065       v  = aa+ai[i];
2066       nz = ai[i+1] - ai[i];
2067       for (j=0; j<nz; j++) rs += PetscAbsScalar(v[j]);
2068       if (rs>sctx.shift_top) sctx.shift_top = rs;
2069     }
2070     sctx.shift_top *= 1.1;
2071     sctx.nshift_max = 5;
2072     sctx.shift_lo   = 0.;
2073     sctx.shift_hi   = 1.;
2074   }
2075 
2076   ierr = ISGetIndices(ip,&rip);CHKERRQ(ierr);
2077   ierr = ISGetIndices(iip,&riip);CHKERRQ(ierr);
2078 
2079   /* allocate working arrays
2080      c2r: linked list, keep track of pivot rows for a given column. c2r[col]: head of the list for a given col
2081      il:  for active k row, il[i] gives the index of the 1st nonzero entry in U[i,k:n-1] in bj and ba arrays
2082   */
2083   ierr = PetscMalloc3(mbs,&rtmp,mbs,&il,mbs,&c2r);CHKERRQ(ierr);
2084 
2085   do {
2086     sctx.newshift = PETSC_FALSE;
2087 
2088     for (i=0; i<mbs; i++) c2r[i] = mbs;
2089     if (mbs) il[0] = 0;
2090 
2091     for (k = 0; k<mbs; k++) {
2092       /* zero rtmp */
2093       nz    = bi[k+1] - bi[k];
2094       bjtmp = bj + bi[k];
2095       for (j=0; j<nz; j++) rtmp[bjtmp[j]] = 0.0;
2096 
2097       /* load in initial unfactored row */
2098       bval = ba + bi[k];
2099       jmin = ai[rip[k]]; jmax = ai[rip[k]+1];
2100       for (j = jmin; j < jmax; j++) {
2101         col = riip[aj[j]];
2102         if (col >= k) { /* only take upper triangular entry */
2103           rtmp[col] = aa[j];
2104           *bval++   = 0.0; /* for in-place factorization */
2105         }
2106       }
2107       /* shift the diagonal of the matrix: ZeropivotApply() */
2108       rtmp[k] += sctx.shift_amount;  /* shift the diagonal of the matrix */
2109 
2110       /* modify k-th row by adding in those rows i with U(i,k)!=0 */
2111       dk = rtmp[k];
2112       i  = c2r[k]; /* first row to be added to k_th row  */
2113 
2114       while (i < k) {
2115         nexti = c2r[i]; /* next row to be added to k_th row */
2116 
2117         /* compute multiplier, update diag(k) and U(i,k) */
2118         ili     = il[i]; /* index of first nonzero element in U(i,k:bms-1) */
2119         uikdi   = -ba[ili]*ba[bdiag[i]]; /* diagonal(k) */
2120         dk     += uikdi*ba[ili]; /* update diag[k] */
2121         ba[ili] = uikdi; /* -U(i,k) */
2122 
2123         /* add multiple of row i to k-th row */
2124         jmin = ili + 1; jmax = bi[i+1];
2125         if (jmin < jmax) {
2126           for (j=jmin; j<jmax; j++) rtmp[bj[j]] += uikdi*ba[j];
2127           /* update il and c2r for row i */
2128           il[i] = jmin;
2129           j     = bj[jmin]; c2r[i] = c2r[j]; c2r[j] = i;
2130         }
2131         i = nexti;
2132       }
2133 
2134       /* copy data into U(k,:) */
2135       rs   = 0.0;
2136       jmin = bi[k]; jmax = bi[k+1]-1;
2137       if (jmin < jmax) {
2138         for (j=jmin; j<jmax; j++) {
2139           col = bj[j]; ba[j] = rtmp[col]; rs += PetscAbsScalar(ba[j]);
2140         }
2141         /* add the k-th row into il and c2r */
2142         il[k] = jmin;
2143         i     = bj[jmin]; c2r[k] = c2r[i]; c2r[i] = k;
2144       }
2145 
2146       /* MatPivotCheck() */
2147       sctx.rs = rs;
2148       sctx.pv = dk;
2149       ierr    = MatPivotCheck(B,A,info,&sctx,i);CHKERRQ(ierr);
2150       if (sctx.newshift) break;
2151       dk = sctx.pv;
2152 
2153       ba[bdiag[k]] = 1.0/dk; /* U(k,k) */
2154     }
2155   } while (sctx.newshift);
2156 
2157   ierr = PetscFree3(rtmp,il,c2r);CHKERRQ(ierr);
2158   ierr = ISRestoreIndices(ip,&rip);CHKERRQ(ierr);
2159   ierr = ISRestoreIndices(iip,&riip);CHKERRQ(ierr);
2160 
2161   ierr = ISIdentity(ip,&perm_identity);CHKERRQ(ierr);
2162   if (perm_identity) {
2163     B->ops->solve          = MatSolve_SeqSBAIJ_1_NaturalOrdering;
2164     B->ops->solvetranspose = MatSolve_SeqSBAIJ_1_NaturalOrdering;
2165     B->ops->forwardsolve   = MatForwardSolve_SeqSBAIJ_1_NaturalOrdering;
2166     B->ops->backwardsolve  = MatBackwardSolve_SeqSBAIJ_1_NaturalOrdering;
2167   } else {
2168     B->ops->solve          = MatSolve_SeqSBAIJ_1;
2169     B->ops->solvetranspose = MatSolve_SeqSBAIJ_1;
2170     B->ops->forwardsolve   = MatForwardSolve_SeqSBAIJ_1;
2171     B->ops->backwardsolve  = MatBackwardSolve_SeqSBAIJ_1;
2172   }
2173 
2174   C->assembled    = PETSC_TRUE;
2175   C->preallocated = PETSC_TRUE;
2176 
2177   ierr = PetscLogFlops(C->rmap->n);CHKERRQ(ierr);
2178 
2179   /* MatPivotView() */
2180   if (sctx.nshift) {
2181     if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE) {
2182       ierr = PetscInfo4(A,"number of shift_pd tries %D, shift_amount %g, diagonal shifted up by %e fraction top_value %e\n",sctx.nshift,(double)sctx.shift_amount,(double)sctx.shift_fraction,(double)sctx.shift_top);CHKERRQ(ierr);
2183     } else if (info->shifttype == (PetscReal)MAT_SHIFT_NONZERO) {
2184       ierr = PetscInfo2(A,"number of shift_nz tries %D, shift_amount %g\n",sctx.nshift,(double)sctx.shift_amount);CHKERRQ(ierr);
2185     } else if (info->shifttype == (PetscReal)MAT_SHIFT_INBLOCKS) {
2186       ierr = PetscInfo2(A,"number of shift_inblocks applied %D, each shift_amount %g\n",sctx.nshift,(double)info->shiftamount);CHKERRQ(ierr);
2187     }
2188   }
2189   PetscFunctionReturn(0);
2190 }
2191 
2192 PetscErrorCode MatCholeskyFactorNumeric_SeqAIJ_inplace(Mat B,Mat A,const MatFactorInfo *info)
2193 {
2194   Mat            C = B;
2195   Mat_SeqAIJ     *a=(Mat_SeqAIJ*)A->data;
2196   Mat_SeqSBAIJ   *b=(Mat_SeqSBAIJ*)C->data;
2197   IS             ip=b->row,iip = b->icol;
2198   PetscErrorCode ierr;
2199   const PetscInt *rip,*riip;
2200   PetscInt       i,j,mbs=A->rmap->n,*bi=b->i,*bj=b->j,*bcol,*bjtmp;
2201   PetscInt       *ai=a->i,*aj=a->j;
2202   PetscInt       k,jmin,jmax,*jl,*il,col,nexti,ili,nz;
2203   MatScalar      *rtmp,*ba=b->a,*bval,*aa=a->a,dk,uikdi;
2204   PetscBool      perm_identity;
2205   FactorShiftCtx sctx;
2206   PetscReal      rs;
2207   MatScalar      d,*v;
2208 
2209   PetscFunctionBegin;
2210   /* MatPivotSetUp(): initialize shift context sctx */
2211   ierr = PetscMemzero(&sctx,sizeof(FactorShiftCtx));CHKERRQ(ierr);
2212 
2213   if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE) { /* set sctx.shift_top=max{rs} */
2214     sctx.shift_top = info->zeropivot;
2215     for (i=0; i<mbs; i++) {
2216       /* calculate sum(|aij|)-RealPart(aii), amt of shift needed for this row */
2217       d  = (aa)[a->diag[i]];
2218       rs = -PetscAbsScalar(d) - PetscRealPart(d);
2219       v  = aa+ai[i];
2220       nz = ai[i+1] - ai[i];
2221       for (j=0; j<nz; j++) rs += PetscAbsScalar(v[j]);
2222       if (rs>sctx.shift_top) sctx.shift_top = rs;
2223     }
2224     sctx.shift_top *= 1.1;
2225     sctx.nshift_max = 5;
2226     sctx.shift_lo   = 0.;
2227     sctx.shift_hi   = 1.;
2228   }
2229 
2230   ierr = ISGetIndices(ip,&rip);CHKERRQ(ierr);
2231   ierr = ISGetIndices(iip,&riip);CHKERRQ(ierr);
2232 
2233   /* initialization */
2234   ierr = PetscMalloc3(mbs,&rtmp,mbs,&il,mbs,&jl);CHKERRQ(ierr);
2235 
2236   do {
2237     sctx.newshift = PETSC_FALSE;
2238 
2239     for (i=0; i<mbs; i++) jl[i] = mbs;
2240     il[0] = 0;
2241 
2242     for (k = 0; k<mbs; k++) {
2243       /* zero rtmp */
2244       nz    = bi[k+1] - bi[k];
2245       bjtmp = bj + bi[k];
2246       for (j=0; j<nz; j++) rtmp[bjtmp[j]] = 0.0;
2247 
2248       bval = ba + bi[k];
2249       /* initialize k-th row by the perm[k]-th row of A */
2250       jmin = ai[rip[k]]; jmax = ai[rip[k]+1];
2251       for (j = jmin; j < jmax; j++) {
2252         col = riip[aj[j]];
2253         if (col >= k) { /* only take upper triangular entry */
2254           rtmp[col] = aa[j];
2255           *bval++   = 0.0; /* for in-place factorization */
2256         }
2257       }
2258       /* shift the diagonal of the matrix */
2259       if (sctx.nshift) rtmp[k] += sctx.shift_amount;
2260 
2261       /* modify k-th row by adding in those rows i with U(i,k)!=0 */
2262       dk = rtmp[k];
2263       i  = jl[k]; /* first row to be added to k_th row  */
2264 
2265       while (i < k) {
2266         nexti = jl[i]; /* next row to be added to k_th row */
2267 
2268         /* compute multiplier, update diag(k) and U(i,k) */
2269         ili     = il[i]; /* index of first nonzero element in U(i,k:bms-1) */
2270         uikdi   = -ba[ili]*ba[bi[i]]; /* diagonal(k) */
2271         dk     += uikdi*ba[ili];
2272         ba[ili] = uikdi; /* -U(i,k) */
2273 
2274         /* add multiple of row i to k-th row */
2275         jmin = ili + 1; jmax = bi[i+1];
2276         if (jmin < jmax) {
2277           for (j=jmin; j<jmax; j++) rtmp[bj[j]] += uikdi*ba[j];
2278           /* update il and jl for row i */
2279           il[i] = jmin;
2280           j     = bj[jmin]; jl[i] = jl[j]; jl[j] = i;
2281         }
2282         i = nexti;
2283       }
2284 
2285       /* shift the diagonals when zero pivot is detected */
2286       /* compute rs=sum of abs(off-diagonal) */
2287       rs   = 0.0;
2288       jmin = bi[k]+1;
2289       nz   = bi[k+1] - jmin;
2290       bcol = bj + jmin;
2291       for (j=0; j<nz; j++) {
2292         rs += PetscAbsScalar(rtmp[bcol[j]]);
2293       }
2294 
2295       sctx.rs = rs;
2296       sctx.pv = dk;
2297       ierr    = MatPivotCheck(B,A,info,&sctx,k);CHKERRQ(ierr);
2298       if (sctx.newshift) break;
2299       dk = sctx.pv;
2300 
2301       /* copy data into U(k,:) */
2302       ba[bi[k]] = 1.0/dk; /* U(k,k) */
2303       jmin      = bi[k]+1; jmax = bi[k+1];
2304       if (jmin < jmax) {
2305         for (j=jmin; j<jmax; j++) {
2306           col = bj[j]; ba[j] = rtmp[col];
2307         }
2308         /* add the k-th row into il and jl */
2309         il[k] = jmin;
2310         i     = bj[jmin]; jl[k] = jl[i]; jl[i] = k;
2311       }
2312     }
2313   } while (sctx.newshift);
2314 
2315   ierr = PetscFree3(rtmp,il,jl);CHKERRQ(ierr);
2316   ierr = ISRestoreIndices(ip,&rip);CHKERRQ(ierr);
2317   ierr = ISRestoreIndices(iip,&riip);CHKERRQ(ierr);
2318 
2319   ierr = ISIdentity(ip,&perm_identity);CHKERRQ(ierr);
2320   if (perm_identity) {
2321     B->ops->solve          = MatSolve_SeqSBAIJ_1_NaturalOrdering_inplace;
2322     B->ops->solvetranspose = MatSolve_SeqSBAIJ_1_NaturalOrdering_inplace;
2323     B->ops->forwardsolve   = MatForwardSolve_SeqSBAIJ_1_NaturalOrdering_inplace;
2324     B->ops->backwardsolve  = MatBackwardSolve_SeqSBAIJ_1_NaturalOrdering_inplace;
2325   } else {
2326     B->ops->solve          = MatSolve_SeqSBAIJ_1_inplace;
2327     B->ops->solvetranspose = MatSolve_SeqSBAIJ_1_inplace;
2328     B->ops->forwardsolve   = MatForwardSolve_SeqSBAIJ_1_inplace;
2329     B->ops->backwardsolve  = MatBackwardSolve_SeqSBAIJ_1_inplace;
2330   }
2331 
2332   C->assembled    = PETSC_TRUE;
2333   C->preallocated = PETSC_TRUE;
2334 
2335   ierr = PetscLogFlops(C->rmap->n);CHKERRQ(ierr);
2336   if (sctx.nshift) {
2337     if (info->shifttype == (PetscReal)MAT_SHIFT_NONZERO) {
2338       ierr = PetscInfo2(A,"number of shiftnz tries %D, shift_amount %g\n",sctx.nshift,(double)sctx.shift_amount);CHKERRQ(ierr);
2339     } else if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE) {
2340       ierr = PetscInfo2(A,"number of shiftpd tries %D, shift_amount %g\n",sctx.nshift,(double)sctx.shift_amount);CHKERRQ(ierr);
2341     }
2342   }
2343   PetscFunctionReturn(0);
2344 }
2345 
2346 /*
2347    icc() under revised new data structure.
2348    Factored arrays bj and ba are stored as
2349      U(0,:),...,U(i,:),U(n-1,:)
2350 
2351    ui=fact->i is an array of size n+1, in which
2352    ui+
2353      ui[i]:  points to 1st entry of U(i,:),i=0,...,n-1
2354      ui[n]:  points to U(n-1,n-1)+1
2355 
2356   udiag=fact->diag is an array of size n,in which
2357      udiag[i]: points to diagonal of U(i,:), i=0,...,n-1
2358 
2359    U(i,:) contains udiag[i] as its last entry, i.e.,
2360     U(i,:) = (u[i,i+1],...,u[i,n-1],diag[i])
2361 */
2362 
2363 PetscErrorCode MatICCFactorSymbolic_SeqAIJ(Mat fact,Mat A,IS perm,const MatFactorInfo *info)
2364 {
2365   Mat_SeqAIJ         *a = (Mat_SeqAIJ*)A->data;
2366   Mat_SeqSBAIJ       *b;
2367   PetscErrorCode     ierr;
2368   PetscBool          perm_identity,missing;
2369   PetscInt           reallocs=0,i,*ai=a->i,*aj=a->j,am=A->rmap->n,*ui,*udiag;
2370   const PetscInt     *rip,*riip;
2371   PetscInt           jmin,jmax,nzk,k,j,*jl,prow,*il,nextprow;
2372   PetscInt           nlnk,*lnk,*lnk_lvl=NULL,d;
2373   PetscInt           ncols,ncols_upper,*cols,*ajtmp,*uj,**uj_ptr,**uj_lvl_ptr;
2374   PetscReal          fill          =info->fill,levels=info->levels;
2375   PetscFreeSpaceList free_space    =NULL,current_space=NULL;
2376   PetscFreeSpaceList free_space_lvl=NULL,current_space_lvl=NULL;
2377   PetscBT            lnkbt;
2378   IS                 iperm;
2379 
2380   PetscFunctionBegin;
2381   if (A->rmap->n != A->cmap->n) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Must be square matrix, rows %D columns %D",A->rmap->n,A->cmap->n);
2382   ierr = MatMissingDiagonal(A,&missing,&d);CHKERRQ(ierr);
2383   if (missing) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Matrix is missing diagonal entry %D",d);
2384   ierr = ISIdentity(perm,&perm_identity);CHKERRQ(ierr);
2385   ierr = ISInvertPermutation(perm,PETSC_DECIDE,&iperm);CHKERRQ(ierr);
2386 
2387   ierr  = PetscMalloc1(am+1,&ui);CHKERRQ(ierr);
2388   ierr  = PetscMalloc1(am+1,&udiag);CHKERRQ(ierr);
2389   ui[0] = 0;
2390 
2391   /* ICC(0) without matrix ordering: simply rearrange column indices */
2392   if (!levels && perm_identity) {
2393     for (i=0; i<am; i++) {
2394       ncols    = ai[i+1] - a->diag[i];
2395       ui[i+1]  = ui[i] + ncols;
2396       udiag[i] = ui[i+1] - 1; /* points to the last entry of U(i,:) */
2397     }
2398     ierr = PetscMalloc1(ui[am]+1,&uj);CHKERRQ(ierr);
2399     cols = uj;
2400     for (i=0; i<am; i++) {
2401       aj    = a->j + a->diag[i] + 1; /* 1st entry of U(i,:) without diagonal */
2402       ncols = ai[i+1] - a->diag[i] -1;
2403       for (j=0; j<ncols; j++) *cols++ = aj[j];
2404       *cols++ = i; /* diagoanl is located as the last entry of U(i,:) */
2405     }
2406   } else { /* case: levels>0 || (levels=0 && !perm_identity) */
2407     ierr = ISGetIndices(iperm,&riip);CHKERRQ(ierr);
2408     ierr = ISGetIndices(perm,&rip);CHKERRQ(ierr);
2409 
2410     /* initialization */
2411     ierr = PetscMalloc1(am+1,&ajtmp);CHKERRQ(ierr);
2412 
2413     /* jl: linked list for storing indices of the pivot rows
2414        il: il[i] points to the 1st nonzero entry of U(i,k:am-1) */
2415     ierr = PetscMalloc4(am,&uj_ptr,am,&uj_lvl_ptr,am,&jl,am,&il);CHKERRQ(ierr);
2416     for (i=0; i<am; i++) {
2417       jl[i] = am; il[i] = 0;
2418     }
2419 
2420     /* create and initialize a linked list for storing column indices of the active row k */
2421     nlnk = am + 1;
2422     ierr = PetscIncompleteLLCreate(am,am,nlnk,lnk,lnk_lvl,lnkbt);CHKERRQ(ierr);
2423 
2424     /* initial FreeSpace size is fill*(ai[am]+am)/2 */
2425     ierr              = PetscFreeSpaceGet(PetscRealIntMultTruncate(fill,(ai[am]+am)/2),&free_space);CHKERRQ(ierr);
2426     current_space     = free_space;
2427     ierr              = PetscFreeSpaceGet(PetscRealIntMultTruncate(fill,(ai[am]+am)/2),&free_space_lvl);CHKERRQ(ierr);
2428     current_space_lvl = free_space_lvl;
2429 
2430     for (k=0; k<am; k++) {  /* for each active row k */
2431       /* initialize lnk by the column indices of row rip[k] of A */
2432       nzk   = 0;
2433       ncols = ai[rip[k]+1] - ai[rip[k]];
2434       if (!ncols) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_MAT_CH_ZRPVT,"Empty row in matrix: row in original ordering %D in permuted ordering %D",rip[k],k);
2435       ncols_upper = 0;
2436       for (j=0; j<ncols; j++) {
2437         i = *(aj + ai[rip[k]] + j); /* unpermuted column index */
2438         if (riip[i] >= k) { /* only take upper triangular entry */
2439           ajtmp[ncols_upper] = i;
2440           ncols_upper++;
2441         }
2442       }
2443       ierr = PetscIncompleteLLInit(ncols_upper,ajtmp,am,riip,nlnk,lnk,lnk_lvl,lnkbt);CHKERRQ(ierr);
2444       nzk += nlnk;
2445 
2446       /* update lnk by computing fill-in for each pivot row to be merged in */
2447       prow = jl[k]; /* 1st pivot row */
2448 
2449       while (prow < k) {
2450         nextprow = jl[prow];
2451 
2452         /* merge prow into k-th row */
2453         jmin  = il[prow] + 1; /* index of the 2nd nzero entry in U(prow,k:am-1) */
2454         jmax  = ui[prow+1];
2455         ncols = jmax-jmin;
2456         i     = jmin - ui[prow];
2457         cols  = uj_ptr[prow] + i; /* points to the 2nd nzero entry in U(prow,k:am-1) */
2458         uj    = uj_lvl_ptr[prow] + i; /* levels of cols */
2459         j     = *(uj - 1);
2460         ierr  = PetscICCLLAddSorted(ncols,cols,levels,uj,am,nlnk,lnk,lnk_lvl,lnkbt,j);CHKERRQ(ierr);
2461         nzk  += nlnk;
2462 
2463         /* update il and jl for prow */
2464         if (jmin < jmax) {
2465           il[prow] = jmin;
2466           j        = *cols; jl[prow] = jl[j]; jl[j] = prow;
2467         }
2468         prow = nextprow;
2469       }
2470 
2471       /* if free space is not available, make more free space */
2472       if (current_space->local_remaining<nzk) {
2473         i    = am - k + 1; /* num of unfactored rows */
2474         i    = PetscIntMultTruncate(i,PetscMin(nzk, i-1)); /* i*nzk, i*(i-1): estimated and max additional space needed */
2475         ierr = PetscFreeSpaceGet(i,&current_space);CHKERRQ(ierr);
2476         ierr = PetscFreeSpaceGet(i,&current_space_lvl);CHKERRQ(ierr);
2477         reallocs++;
2478       }
2479 
2480       /* copy data into free_space and free_space_lvl, then initialize lnk */
2481       if (nzk == 0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Empty row %D in ICC matrix factor",k);
2482       ierr = PetscIncompleteLLClean(am,am,nzk,lnk,lnk_lvl,current_space->array,current_space_lvl->array,lnkbt);CHKERRQ(ierr);
2483 
2484       /* add the k-th row into il and jl */
2485       if (nzk > 1) {
2486         i     = current_space->array[1]; /* col value of the first nonzero element in U(k, k+1:am-1) */
2487         jl[k] = jl[i]; jl[i] = k;
2488         il[k] = ui[k] + 1;
2489       }
2490       uj_ptr[k]     = current_space->array;
2491       uj_lvl_ptr[k] = current_space_lvl->array;
2492 
2493       current_space->array           += nzk;
2494       current_space->local_used      += nzk;
2495       current_space->local_remaining -= nzk;
2496 
2497       current_space_lvl->array           += nzk;
2498       current_space_lvl->local_used      += nzk;
2499       current_space_lvl->local_remaining -= nzk;
2500 
2501       ui[k+1] = ui[k] + nzk;
2502     }
2503 
2504     ierr = ISRestoreIndices(perm,&rip);CHKERRQ(ierr);
2505     ierr = ISRestoreIndices(iperm,&riip);CHKERRQ(ierr);
2506     ierr = PetscFree4(uj_ptr,uj_lvl_ptr,jl,il);CHKERRQ(ierr);
2507     ierr = PetscFree(ajtmp);CHKERRQ(ierr);
2508 
2509     /* copy free_space into uj and free free_space; set ui, uj, udiag in new datastructure; */
2510     ierr = PetscMalloc1(ui[am]+1,&uj);CHKERRQ(ierr);
2511     ierr = PetscFreeSpaceContiguous_Cholesky(&free_space,uj,am,ui,udiag);CHKERRQ(ierr); /* store matrix factor  */
2512     ierr = PetscIncompleteLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
2513     ierr = PetscFreeSpaceDestroy(free_space_lvl);CHKERRQ(ierr);
2514 
2515   } /* end of case: levels>0 || (levels=0 && !perm_identity) */
2516 
2517   /* put together the new matrix in MATSEQSBAIJ format */
2518   b               = (Mat_SeqSBAIJ*)(fact)->data;
2519   b->singlemalloc = PETSC_FALSE;
2520 
2521   ierr = PetscMalloc1(ui[am]+1,&b->a);CHKERRQ(ierr);
2522 
2523   b->j             = uj;
2524   b->i             = ui;
2525   b->diag          = udiag;
2526   b->free_diag     = PETSC_TRUE;
2527   b->ilen          = 0;
2528   b->imax          = 0;
2529   b->row           = perm;
2530   b->col           = perm;
2531   ierr             = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr);
2532   ierr             = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr);
2533   b->icol          = iperm;
2534   b->pivotinblocks = PETSC_FALSE; /* need to get from MatFactorInfo */
2535 
2536   ierr = PetscMalloc1(am+1,&b->solve_work);CHKERRQ(ierr);
2537   ierr = PetscLogObjectMemory((PetscObject)fact,ui[am]*(sizeof(PetscInt)+sizeof(MatScalar)));CHKERRQ(ierr);
2538 
2539   b->maxnz   = b->nz = ui[am];
2540   b->free_a  = PETSC_TRUE;
2541   b->free_ij = PETSC_TRUE;
2542 
2543   fact->info.factor_mallocs   = reallocs;
2544   fact->info.fill_ratio_given = fill;
2545   if (ai[am] != 0) {
2546     /* nonzeros in lower triangular part of A (including diagonals) = (ai[am]+am)/2 */
2547     fact->info.fill_ratio_needed = ((PetscReal)2*ui[am])/(ai[am]+am);
2548   } else {
2549     fact->info.fill_ratio_needed = 0.0;
2550   }
2551 #if defined(PETSC_USE_INFO)
2552   if (ai[am] != 0) {
2553     PetscReal af = fact->info.fill_ratio_needed;
2554     ierr = PetscInfo3(A,"Reallocs %D Fill ratio:given %g needed %g\n",reallocs,(double)fill,(double)af);CHKERRQ(ierr);
2555     ierr = PetscInfo1(A,"Run with -pc_factor_fill %g or use \n",(double)af);CHKERRQ(ierr);
2556     ierr = PetscInfo1(A,"PCFactorSetFill(pc,%g) for best performance.\n",(double)af);CHKERRQ(ierr);
2557   } else {
2558     ierr = PetscInfo(A,"Empty matrix.\n");CHKERRQ(ierr);
2559   }
2560 #endif
2561   fact->ops->choleskyfactornumeric = MatCholeskyFactorNumeric_SeqAIJ;
2562   PetscFunctionReturn(0);
2563 }
2564 
2565 PetscErrorCode MatICCFactorSymbolic_SeqAIJ_inplace(Mat fact,Mat A,IS perm,const MatFactorInfo *info)
2566 {
2567   Mat_SeqAIJ         *a = (Mat_SeqAIJ*)A->data;
2568   Mat_SeqSBAIJ       *b;
2569   PetscErrorCode     ierr;
2570   PetscBool          perm_identity,missing;
2571   PetscInt           reallocs=0,i,*ai=a->i,*aj=a->j,am=A->rmap->n,*ui,*udiag;
2572   const PetscInt     *rip,*riip;
2573   PetscInt           jmin,jmax,nzk,k,j,*jl,prow,*il,nextprow;
2574   PetscInt           nlnk,*lnk,*lnk_lvl=NULL,d;
2575   PetscInt           ncols,ncols_upper,*cols,*ajtmp,*uj,**uj_ptr,**uj_lvl_ptr;
2576   PetscReal          fill          =info->fill,levels=info->levels;
2577   PetscFreeSpaceList free_space    =NULL,current_space=NULL;
2578   PetscFreeSpaceList free_space_lvl=NULL,current_space_lvl=NULL;
2579   PetscBT            lnkbt;
2580   IS                 iperm;
2581 
2582   PetscFunctionBegin;
2583   if (A->rmap->n != A->cmap->n) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Must be square matrix, rows %D columns %D",A->rmap->n,A->cmap->n);
2584   ierr = MatMissingDiagonal(A,&missing,&d);CHKERRQ(ierr);
2585   if (missing) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Matrix is missing diagonal entry %D",d);
2586   ierr = ISIdentity(perm,&perm_identity);CHKERRQ(ierr);
2587   ierr = ISInvertPermutation(perm,PETSC_DECIDE,&iperm);CHKERRQ(ierr);
2588 
2589   ierr  = PetscMalloc1(am+1,&ui);CHKERRQ(ierr);
2590   ierr  = PetscMalloc1(am+1,&udiag);CHKERRQ(ierr);
2591   ui[0] = 0;
2592 
2593   /* ICC(0) without matrix ordering: simply copies fill pattern */
2594   if (!levels && perm_identity) {
2595 
2596     for (i=0; i<am; i++) {
2597       ui[i+1]  = ui[i] + ai[i+1] - a->diag[i];
2598       udiag[i] = ui[i];
2599     }
2600     ierr = PetscMalloc1(ui[am]+1,&uj);CHKERRQ(ierr);
2601     cols = uj;
2602     for (i=0; i<am; i++) {
2603       aj    = a->j + a->diag[i];
2604       ncols = ui[i+1] - ui[i];
2605       for (j=0; j<ncols; j++) *cols++ = *aj++;
2606     }
2607   } else { /* case: levels>0 || (levels=0 && !perm_identity) */
2608     ierr = ISGetIndices(iperm,&riip);CHKERRQ(ierr);
2609     ierr = ISGetIndices(perm,&rip);CHKERRQ(ierr);
2610 
2611     /* initialization */
2612     ierr = PetscMalloc1(am+1,&ajtmp);CHKERRQ(ierr);
2613 
2614     /* jl: linked list for storing indices of the pivot rows
2615        il: il[i] points to the 1st nonzero entry of U(i,k:am-1) */
2616     ierr = PetscMalloc4(am,&uj_ptr,am,&uj_lvl_ptr,am,&jl,am,&il);CHKERRQ(ierr);
2617     for (i=0; i<am; i++) {
2618       jl[i] = am; il[i] = 0;
2619     }
2620 
2621     /* create and initialize a linked list for storing column indices of the active row k */
2622     nlnk = am + 1;
2623     ierr = PetscIncompleteLLCreate(am,am,nlnk,lnk,lnk_lvl,lnkbt);CHKERRQ(ierr);
2624 
2625     /* initial FreeSpace size is fill*(ai[am]+1) */
2626     ierr              = PetscFreeSpaceGet(PetscRealIntMultTruncate(fill,ai[am]+1),&free_space);CHKERRQ(ierr);
2627     current_space     = free_space;
2628     ierr              = PetscFreeSpaceGet(PetscRealIntMultTruncate(fill,ai[am]+1),&free_space_lvl);CHKERRQ(ierr);
2629     current_space_lvl = free_space_lvl;
2630 
2631     for (k=0; k<am; k++) {  /* for each active row k */
2632       /* initialize lnk by the column indices of row rip[k] of A */
2633       nzk   = 0;
2634       ncols = ai[rip[k]+1] - ai[rip[k]];
2635       if (!ncols) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_MAT_CH_ZRPVT,"Empty row in matrix: row in original ordering %D in permuted ordering %D",rip[k],k);
2636       ncols_upper = 0;
2637       for (j=0; j<ncols; j++) {
2638         i = *(aj + ai[rip[k]] + j); /* unpermuted column index */
2639         if (riip[i] >= k) { /* only take upper triangular entry */
2640           ajtmp[ncols_upper] = i;
2641           ncols_upper++;
2642         }
2643       }
2644       ierr = PetscIncompleteLLInit(ncols_upper,ajtmp,am,riip,nlnk,lnk,lnk_lvl,lnkbt);CHKERRQ(ierr);
2645       nzk += nlnk;
2646 
2647       /* update lnk by computing fill-in for each pivot row to be merged in */
2648       prow = jl[k]; /* 1st pivot row */
2649 
2650       while (prow < k) {
2651         nextprow = jl[prow];
2652 
2653         /* merge prow into k-th row */
2654         jmin  = il[prow] + 1; /* index of the 2nd nzero entry in U(prow,k:am-1) */
2655         jmax  = ui[prow+1];
2656         ncols = jmax-jmin;
2657         i     = jmin - ui[prow];
2658         cols  = uj_ptr[prow] + i; /* points to the 2nd nzero entry in U(prow,k:am-1) */
2659         uj    = uj_lvl_ptr[prow] + i; /* levels of cols */
2660         j     = *(uj - 1);
2661         ierr  = PetscICCLLAddSorted(ncols,cols,levels,uj,am,nlnk,lnk,lnk_lvl,lnkbt,j);CHKERRQ(ierr);
2662         nzk  += nlnk;
2663 
2664         /* update il and jl for prow */
2665         if (jmin < jmax) {
2666           il[prow] = jmin;
2667           j        = *cols; jl[prow] = jl[j]; jl[j] = prow;
2668         }
2669         prow = nextprow;
2670       }
2671 
2672       /* if free space is not available, make more free space */
2673       if (current_space->local_remaining<nzk) {
2674         i    = am - k + 1; /* num of unfactored rows */
2675         i    = PetscIntMultTruncate(i,PetscMin(nzk, i-1)); /* i*nzk, i*(i-1): estimated and max additional space needed */
2676         ierr = PetscFreeSpaceGet(i,&current_space);CHKERRQ(ierr);
2677         ierr = PetscFreeSpaceGet(i,&current_space_lvl);CHKERRQ(ierr);
2678         reallocs++;
2679       }
2680 
2681       /* copy data into free_space and free_space_lvl, then initialize lnk */
2682       if (!nzk) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Empty row %D in ICC matrix factor",k);
2683       ierr = PetscIncompleteLLClean(am,am,nzk,lnk,lnk_lvl,current_space->array,current_space_lvl->array,lnkbt);CHKERRQ(ierr);
2684 
2685       /* add the k-th row into il and jl */
2686       if (nzk > 1) {
2687         i     = current_space->array[1]; /* col value of the first nonzero element in U(k, k+1:am-1) */
2688         jl[k] = jl[i]; jl[i] = k;
2689         il[k] = ui[k] + 1;
2690       }
2691       uj_ptr[k]     = current_space->array;
2692       uj_lvl_ptr[k] = current_space_lvl->array;
2693 
2694       current_space->array           += nzk;
2695       current_space->local_used      += nzk;
2696       current_space->local_remaining -= nzk;
2697 
2698       current_space_lvl->array           += nzk;
2699       current_space_lvl->local_used      += nzk;
2700       current_space_lvl->local_remaining -= nzk;
2701 
2702       ui[k+1] = ui[k] + nzk;
2703     }
2704 
2705 #if defined(PETSC_USE_INFO)
2706     if (ai[am] != 0) {
2707       PetscReal af = (PetscReal)ui[am]/((PetscReal)ai[am]);
2708       ierr = PetscInfo3(A,"Reallocs %D Fill ratio:given %g needed %g\n",reallocs,(double)fill,(double)af);CHKERRQ(ierr);
2709       ierr = PetscInfo1(A,"Run with -pc_factor_fill %g or use \n",(double)af);CHKERRQ(ierr);
2710       ierr = PetscInfo1(A,"PCFactorSetFill(pc,%g) for best performance.\n",(double)af);CHKERRQ(ierr);
2711     } else {
2712       ierr = PetscInfo(A,"Empty matrix.\n");CHKERRQ(ierr);
2713     }
2714 #endif
2715 
2716     ierr = ISRestoreIndices(perm,&rip);CHKERRQ(ierr);
2717     ierr = ISRestoreIndices(iperm,&riip);CHKERRQ(ierr);
2718     ierr = PetscFree4(uj_ptr,uj_lvl_ptr,jl,il);CHKERRQ(ierr);
2719     ierr = PetscFree(ajtmp);CHKERRQ(ierr);
2720 
2721     /* destroy list of free space and other temporary array(s) */
2722     ierr = PetscMalloc1(ui[am]+1,&uj);CHKERRQ(ierr);
2723     ierr = PetscFreeSpaceContiguous(&free_space,uj);CHKERRQ(ierr);
2724     ierr = PetscIncompleteLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
2725     ierr = PetscFreeSpaceDestroy(free_space_lvl);CHKERRQ(ierr);
2726 
2727   } /* end of case: levels>0 || (levels=0 && !perm_identity) */
2728 
2729   /* put together the new matrix in MATSEQSBAIJ format */
2730 
2731   b               = (Mat_SeqSBAIJ*)fact->data;
2732   b->singlemalloc = PETSC_FALSE;
2733 
2734   ierr = PetscMalloc1(ui[am]+1,&b->a);CHKERRQ(ierr);
2735 
2736   b->j         = uj;
2737   b->i         = ui;
2738   b->diag      = udiag;
2739   b->free_diag = PETSC_TRUE;
2740   b->ilen      = 0;
2741   b->imax      = 0;
2742   b->row       = perm;
2743   b->col       = perm;
2744 
2745   ierr = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr);
2746   ierr = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr);
2747 
2748   b->icol          = iperm;
2749   b->pivotinblocks = PETSC_FALSE; /* need to get from MatFactorInfo */
2750   ierr             = PetscMalloc1(am+1,&b->solve_work);CHKERRQ(ierr);
2751   ierr             = PetscLogObjectMemory((PetscObject)fact,(ui[am]-am)*(sizeof(PetscInt)+sizeof(MatScalar)));CHKERRQ(ierr);
2752   b->maxnz         = b->nz = ui[am];
2753   b->free_a        = PETSC_TRUE;
2754   b->free_ij       = PETSC_TRUE;
2755 
2756   fact->info.factor_mallocs   = reallocs;
2757   fact->info.fill_ratio_given = fill;
2758   if (ai[am] != 0) {
2759     fact->info.fill_ratio_needed = ((PetscReal)ui[am])/((PetscReal)ai[am]);
2760   } else {
2761     fact->info.fill_ratio_needed = 0.0;
2762   }
2763   fact->ops->choleskyfactornumeric = MatCholeskyFactorNumeric_SeqAIJ_inplace;
2764   PetscFunctionReturn(0);
2765 }
2766 
2767 PetscErrorCode MatCholeskyFactorSymbolic_SeqAIJ(Mat fact,Mat A,IS perm,const MatFactorInfo *info)
2768 {
2769   Mat_SeqAIJ         *a = (Mat_SeqAIJ*)A->data;
2770   Mat_SeqSBAIJ       *b;
2771   PetscErrorCode     ierr;
2772   PetscBool          perm_identity,missing;
2773   PetscReal          fill = info->fill;
2774   const PetscInt     *rip,*riip;
2775   PetscInt           i,am=A->rmap->n,*ai=a->i,*aj=a->j,reallocs=0,prow;
2776   PetscInt           *jl,jmin,jmax,nzk,*ui,k,j,*il,nextprow;
2777   PetscInt           nlnk,*lnk,ncols,ncols_upper,*cols,*uj,**ui_ptr,*uj_ptr,*udiag;
2778   PetscFreeSpaceList free_space=NULL,current_space=NULL;
2779   PetscBT            lnkbt;
2780   IS                 iperm;
2781 
2782   PetscFunctionBegin;
2783   if (A->rmap->n != A->cmap->n) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Must be square matrix, rows %D columns %D",A->rmap->n,A->cmap->n);
2784   ierr = MatMissingDiagonal(A,&missing,&i);CHKERRQ(ierr);
2785   if (missing) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Matrix is missing diagonal entry %D",i);
2786 
2787   /* check whether perm is the identity mapping */
2788   ierr = ISIdentity(perm,&perm_identity);CHKERRQ(ierr);
2789   ierr = ISInvertPermutation(perm,PETSC_DECIDE,&iperm);CHKERRQ(ierr);
2790   ierr = ISGetIndices(iperm,&riip);CHKERRQ(ierr);
2791   ierr = ISGetIndices(perm,&rip);CHKERRQ(ierr);
2792 
2793   /* initialization */
2794   ierr  = PetscMalloc1(am+1,&ui);CHKERRQ(ierr);
2795   ierr  = PetscMalloc1(am+1,&udiag);CHKERRQ(ierr);
2796   ui[0] = 0;
2797 
2798   /* jl: linked list for storing indices of the pivot rows
2799      il: il[i] points to the 1st nonzero entry of U(i,k:am-1) */
2800   ierr = PetscMalloc4(am,&ui_ptr,am,&jl,am,&il,am,&cols);CHKERRQ(ierr);
2801   for (i=0; i<am; i++) {
2802     jl[i] = am; il[i] = 0;
2803   }
2804 
2805   /* create and initialize a linked list for storing column indices of the active row k */
2806   nlnk = am + 1;
2807   ierr = PetscLLCreate(am,am,nlnk,lnk,lnkbt);CHKERRQ(ierr);
2808 
2809   /* initial FreeSpace size is fill*(ai[am]+am)/2 */
2810   ierr          = PetscFreeSpaceGet(PetscRealIntMultTruncate(fill,(ai[am]+am)/2),&free_space);CHKERRQ(ierr);
2811   current_space = free_space;
2812 
2813   for (k=0; k<am; k++) {  /* for each active row k */
2814     /* initialize lnk by the column indices of row rip[k] of A */
2815     nzk   = 0;
2816     ncols = ai[rip[k]+1] - ai[rip[k]];
2817     if (!ncols) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_MAT_CH_ZRPVT,"Empty row in matrix: row in original ordering %D in permuted ordering %D",rip[k],k);
2818     ncols_upper = 0;
2819     for (j=0; j<ncols; j++) {
2820       i = riip[*(aj + ai[rip[k]] + j)];
2821       if (i >= k) { /* only take upper triangular entry */
2822         cols[ncols_upper] = i;
2823         ncols_upper++;
2824       }
2825     }
2826     ierr = PetscLLAdd(ncols_upper,cols,am,nlnk,lnk,lnkbt);CHKERRQ(ierr);
2827     nzk += nlnk;
2828 
2829     /* update lnk by computing fill-in for each pivot row to be merged in */
2830     prow = jl[k]; /* 1st pivot row */
2831 
2832     while (prow < k) {
2833       nextprow = jl[prow];
2834       /* merge prow into k-th row */
2835       jmin   = il[prow] + 1; /* index of the 2nd nzero entry in U(prow,k:am-1) */
2836       jmax   = ui[prow+1];
2837       ncols  = jmax-jmin;
2838       uj_ptr = ui_ptr[prow] + jmin - ui[prow]; /* points to the 2nd nzero entry in U(prow,k:am-1) */
2839       ierr   = PetscLLAddSorted(ncols,uj_ptr,am,nlnk,lnk,lnkbt);CHKERRQ(ierr);
2840       nzk   += nlnk;
2841 
2842       /* update il and jl for prow */
2843       if (jmin < jmax) {
2844         il[prow] = jmin;
2845         j        = *uj_ptr;
2846         jl[prow] = jl[j];
2847         jl[j]    = prow;
2848       }
2849       prow = nextprow;
2850     }
2851 
2852     /* if free space is not available, make more free space */
2853     if (current_space->local_remaining<nzk) {
2854       i    = am - k + 1; /* num of unfactored rows */
2855       i    = PetscIntMultTruncate(i,PetscMin(nzk,i-1)); /* i*nzk, i*(i-1): estimated and max additional space needed */
2856       ierr = PetscFreeSpaceGet(i,&current_space);CHKERRQ(ierr);
2857       reallocs++;
2858     }
2859 
2860     /* copy data into free space, then initialize lnk */
2861     ierr = PetscLLClean(am,am,nzk,lnk,current_space->array,lnkbt);CHKERRQ(ierr);
2862 
2863     /* add the k-th row into il and jl */
2864     if (nzk > 1) {
2865       i     = current_space->array[1]; /* col value of the first nonzero element in U(k, k+1:am-1) */
2866       jl[k] = jl[i]; jl[i] = k;
2867       il[k] = ui[k] + 1;
2868     }
2869     ui_ptr[k] = current_space->array;
2870 
2871     current_space->array           += nzk;
2872     current_space->local_used      += nzk;
2873     current_space->local_remaining -= nzk;
2874 
2875     ui[k+1] = ui[k] + nzk;
2876   }
2877 
2878   ierr = ISRestoreIndices(perm,&rip);CHKERRQ(ierr);
2879   ierr = ISRestoreIndices(iperm,&riip);CHKERRQ(ierr);
2880   ierr = PetscFree4(ui_ptr,jl,il,cols);CHKERRQ(ierr);
2881 
2882   /* copy free_space into uj and free free_space; set ui, uj, udiag in new datastructure; */
2883   ierr = PetscMalloc1(ui[am]+1,&uj);CHKERRQ(ierr);
2884   ierr = PetscFreeSpaceContiguous_Cholesky(&free_space,uj,am,ui,udiag);CHKERRQ(ierr); /* store matrix factor */
2885   ierr = PetscLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
2886 
2887   /* put together the new matrix in MATSEQSBAIJ format */
2888 
2889   b               = (Mat_SeqSBAIJ*)fact->data;
2890   b->singlemalloc = PETSC_FALSE;
2891   b->free_a       = PETSC_TRUE;
2892   b->free_ij      = PETSC_TRUE;
2893 
2894   ierr = PetscMalloc1(ui[am]+1,&b->a);CHKERRQ(ierr);
2895 
2896   b->j         = uj;
2897   b->i         = ui;
2898   b->diag      = udiag;
2899   b->free_diag = PETSC_TRUE;
2900   b->ilen      = 0;
2901   b->imax      = 0;
2902   b->row       = perm;
2903   b->col       = perm;
2904 
2905   ierr = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr);
2906   ierr = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr);
2907 
2908   b->icol          = iperm;
2909   b->pivotinblocks = PETSC_FALSE; /* need to get from MatFactorInfo */
2910 
2911   ierr = PetscMalloc1(am+1,&b->solve_work);CHKERRQ(ierr);
2912   ierr = PetscLogObjectMemory((PetscObject)fact,ui[am]*(sizeof(PetscInt)+sizeof(MatScalar)));CHKERRQ(ierr);
2913 
2914   b->maxnz = b->nz = ui[am];
2915 
2916   fact->info.factor_mallocs   = reallocs;
2917   fact->info.fill_ratio_given = fill;
2918   if (ai[am] != 0) {
2919     /* nonzeros in lower triangular part of A (including diagonals) = (ai[am]+am)/2 */
2920     fact->info.fill_ratio_needed = ((PetscReal)2*ui[am])/(ai[am]+am);
2921   } else {
2922     fact->info.fill_ratio_needed = 0.0;
2923   }
2924 #if defined(PETSC_USE_INFO)
2925   if (ai[am] != 0) {
2926     PetscReal af = fact->info.fill_ratio_needed;
2927     ierr = PetscInfo3(A,"Reallocs %D Fill ratio:given %g needed %g\n",reallocs,(double)fill,(double)af);CHKERRQ(ierr);
2928     ierr = PetscInfo1(A,"Run with -pc_factor_fill %g or use \n",(double)af);CHKERRQ(ierr);
2929     ierr = PetscInfo1(A,"PCFactorSetFill(pc,%g) for best performance.\n",(double)af);CHKERRQ(ierr);
2930   } else {
2931     ierr = PetscInfo(A,"Empty matrix.\n");CHKERRQ(ierr);
2932   }
2933 #endif
2934   fact->ops->choleskyfactornumeric = MatCholeskyFactorNumeric_SeqAIJ;
2935   PetscFunctionReturn(0);
2936 }
2937 
2938 PetscErrorCode MatCholeskyFactorSymbolic_SeqAIJ_inplace(Mat fact,Mat A,IS perm,const MatFactorInfo *info)
2939 {
2940   Mat_SeqAIJ         *a = (Mat_SeqAIJ*)A->data;
2941   Mat_SeqSBAIJ       *b;
2942   PetscErrorCode     ierr;
2943   PetscBool          perm_identity,missing;
2944   PetscReal          fill = info->fill;
2945   const PetscInt     *rip,*riip;
2946   PetscInt           i,am=A->rmap->n,*ai=a->i,*aj=a->j,reallocs=0,prow;
2947   PetscInt           *jl,jmin,jmax,nzk,*ui,k,j,*il,nextprow;
2948   PetscInt           nlnk,*lnk,ncols,ncols_upper,*cols,*uj,**ui_ptr,*uj_ptr;
2949   PetscFreeSpaceList free_space=NULL,current_space=NULL;
2950   PetscBT            lnkbt;
2951   IS                 iperm;
2952 
2953   PetscFunctionBegin;
2954   if (A->rmap->n != A->cmap->n) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Must be square matrix, rows %D columns %D",A->rmap->n,A->cmap->n);
2955   ierr = MatMissingDiagonal(A,&missing,&i);CHKERRQ(ierr);
2956   if (missing) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Matrix is missing diagonal entry %D",i);
2957 
2958   /* check whether perm is the identity mapping */
2959   ierr = ISIdentity(perm,&perm_identity);CHKERRQ(ierr);
2960   ierr = ISInvertPermutation(perm,PETSC_DECIDE,&iperm);CHKERRQ(ierr);
2961   ierr = ISGetIndices(iperm,&riip);CHKERRQ(ierr);
2962   ierr = ISGetIndices(perm,&rip);CHKERRQ(ierr);
2963 
2964   /* initialization */
2965   ierr  = PetscMalloc1(am+1,&ui);CHKERRQ(ierr);
2966   ui[0] = 0;
2967 
2968   /* jl: linked list for storing indices of the pivot rows
2969      il: il[i] points to the 1st nonzero entry of U(i,k:am-1) */
2970   ierr = PetscMalloc4(am,&ui_ptr,am,&jl,am,&il,am,&cols);CHKERRQ(ierr);
2971   for (i=0; i<am; i++) {
2972     jl[i] = am; il[i] = 0;
2973   }
2974 
2975   /* create and initialize a linked list for storing column indices of the active row k */
2976   nlnk = am + 1;
2977   ierr = PetscLLCreate(am,am,nlnk,lnk,lnkbt);CHKERRQ(ierr);
2978 
2979   /* initial FreeSpace size is fill*(ai[am]+1) */
2980   ierr          = PetscFreeSpaceGet(PetscRealIntMultTruncate(fill,ai[am]+1),&free_space);CHKERRQ(ierr);
2981   current_space = free_space;
2982 
2983   for (k=0; k<am; k++) {  /* for each active row k */
2984     /* initialize lnk by the column indices of row rip[k] of A */
2985     nzk   = 0;
2986     ncols = ai[rip[k]+1] - ai[rip[k]];
2987     if (!ncols) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_MAT_CH_ZRPVT,"Empty row in matrix: row in original ordering %D in permuted ordering %D",rip[k],k);
2988     ncols_upper = 0;
2989     for (j=0; j<ncols; j++) {
2990       i = riip[*(aj + ai[rip[k]] + j)];
2991       if (i >= k) { /* only take upper triangular entry */
2992         cols[ncols_upper] = i;
2993         ncols_upper++;
2994       }
2995     }
2996     ierr = PetscLLAdd(ncols_upper,cols,am,nlnk,lnk,lnkbt);CHKERRQ(ierr);
2997     nzk += nlnk;
2998 
2999     /* update lnk by computing fill-in for each pivot row to be merged in */
3000     prow = jl[k]; /* 1st pivot row */
3001 
3002     while (prow < k) {
3003       nextprow = jl[prow];
3004       /* merge prow into k-th row */
3005       jmin   = il[prow] + 1; /* index of the 2nd nzero entry in U(prow,k:am-1) */
3006       jmax   = ui[prow+1];
3007       ncols  = jmax-jmin;
3008       uj_ptr = ui_ptr[prow] + jmin - ui[prow]; /* points to the 2nd nzero entry in U(prow,k:am-1) */
3009       ierr   = PetscLLAddSorted(ncols,uj_ptr,am,nlnk,lnk,lnkbt);CHKERRQ(ierr);
3010       nzk   += nlnk;
3011 
3012       /* update il and jl for prow */
3013       if (jmin < jmax) {
3014         il[prow] = jmin;
3015         j        = *uj_ptr; jl[prow] = jl[j]; jl[j] = prow;
3016       }
3017       prow = nextprow;
3018     }
3019 
3020     /* if free space is not available, make more free space */
3021     if (current_space->local_remaining<nzk) {
3022       i    = am - k + 1; /* num of unfactored rows */
3023       i    = PetscMin(i*nzk, i*(i-1)); /* i*nzk, i*(i-1): estimated and max additional space needed */
3024       ierr = PetscFreeSpaceGet(i,&current_space);CHKERRQ(ierr);
3025       reallocs++;
3026     }
3027 
3028     /* copy data into free space, then initialize lnk */
3029     ierr = PetscLLClean(am,am,nzk,lnk,current_space->array,lnkbt);CHKERRQ(ierr);
3030 
3031     /* add the k-th row into il and jl */
3032     if (nzk-1 > 0) {
3033       i     = current_space->array[1]; /* col value of the first nonzero element in U(k, k+1:am-1) */
3034       jl[k] = jl[i]; jl[i] = k;
3035       il[k] = ui[k] + 1;
3036     }
3037     ui_ptr[k] = current_space->array;
3038 
3039     current_space->array           += nzk;
3040     current_space->local_used      += nzk;
3041     current_space->local_remaining -= nzk;
3042 
3043     ui[k+1] = ui[k] + nzk;
3044   }
3045 
3046 #if defined(PETSC_USE_INFO)
3047   if (ai[am] != 0) {
3048     PetscReal af = (PetscReal)(ui[am])/((PetscReal)ai[am]);
3049     ierr = PetscInfo3(A,"Reallocs %D Fill ratio:given %g needed %g\n",reallocs,(double)fill,(double)af);CHKERRQ(ierr);
3050     ierr = PetscInfo1(A,"Run with -pc_factor_fill %g or use \n",(double)af);CHKERRQ(ierr);
3051     ierr = PetscInfo1(A,"PCFactorSetFill(pc,%g) for best performance.\n",(double)af);CHKERRQ(ierr);
3052   } else {
3053     ierr = PetscInfo(A,"Empty matrix.\n");CHKERRQ(ierr);
3054   }
3055 #endif
3056 
3057   ierr = ISRestoreIndices(perm,&rip);CHKERRQ(ierr);
3058   ierr = ISRestoreIndices(iperm,&riip);CHKERRQ(ierr);
3059   ierr = PetscFree4(ui_ptr,jl,il,cols);CHKERRQ(ierr);
3060 
3061   /* destroy list of free space and other temporary array(s) */
3062   ierr = PetscMalloc1(ui[am]+1,&uj);CHKERRQ(ierr);
3063   ierr = PetscFreeSpaceContiguous(&free_space,uj);CHKERRQ(ierr);
3064   ierr = PetscLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
3065 
3066   /* put together the new matrix in MATSEQSBAIJ format */
3067 
3068   b               = (Mat_SeqSBAIJ*)fact->data;
3069   b->singlemalloc = PETSC_FALSE;
3070   b->free_a       = PETSC_TRUE;
3071   b->free_ij      = PETSC_TRUE;
3072 
3073   ierr = PetscMalloc1(ui[am]+1,&b->a);CHKERRQ(ierr);
3074 
3075   b->j    = uj;
3076   b->i    = ui;
3077   b->diag = 0;
3078   b->ilen = 0;
3079   b->imax = 0;
3080   b->row  = perm;
3081   b->col  = perm;
3082 
3083   ierr = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr);
3084   ierr = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr);
3085 
3086   b->icol          = iperm;
3087   b->pivotinblocks = PETSC_FALSE; /* need to get from MatFactorInfo */
3088 
3089   ierr     = PetscMalloc1(am+1,&b->solve_work);CHKERRQ(ierr);
3090   ierr     = PetscLogObjectMemory((PetscObject)fact,(ui[am]-am)*(sizeof(PetscInt)+sizeof(MatScalar)));CHKERRQ(ierr);
3091   b->maxnz = b->nz = ui[am];
3092 
3093   fact->info.factor_mallocs   = reallocs;
3094   fact->info.fill_ratio_given = fill;
3095   if (ai[am] != 0) {
3096     fact->info.fill_ratio_needed = ((PetscReal)ui[am])/((PetscReal)ai[am]);
3097   } else {
3098     fact->info.fill_ratio_needed = 0.0;
3099   }
3100   fact->ops->choleskyfactornumeric = MatCholeskyFactorNumeric_SeqAIJ_inplace;
3101   PetscFunctionReturn(0);
3102 }
3103 
3104 PetscErrorCode MatSolve_SeqAIJ_NaturalOrdering(Mat A,Vec bb,Vec xx)
3105 {
3106   Mat_SeqAIJ        *a = (Mat_SeqAIJ*)A->data;
3107   PetscErrorCode    ierr;
3108   PetscInt          n   = A->rmap->n;
3109   const PetscInt    *ai = a->i,*aj = a->j,*adiag = a->diag,*vi;
3110   PetscScalar       *x,sum;
3111   const PetscScalar *b;
3112   const MatScalar   *aa = a->a,*v;
3113   PetscInt          i,nz;
3114 
3115   PetscFunctionBegin;
3116   if (!n) PetscFunctionReturn(0);
3117 
3118   ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr);
3119   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
3120 
3121   /* forward solve the lower triangular */
3122   x[0] = b[0];
3123   v    = aa;
3124   vi   = aj;
3125   for (i=1; i<n; i++) {
3126     nz  = ai[i+1] - ai[i];
3127     sum = b[i];
3128     PetscSparseDenseMinusDot(sum,x,v,vi,nz);
3129     v   += nz;
3130     vi  += nz;
3131     x[i] = sum;
3132   }
3133 
3134   /* backward solve the upper triangular */
3135   for (i=n-1; i>=0; i--) {
3136     v   = aa + adiag[i+1] + 1;
3137     vi  = aj + adiag[i+1] + 1;
3138     nz  = adiag[i] - adiag[i+1]-1;
3139     sum = x[i];
3140     PetscSparseDenseMinusDot(sum,x,v,vi,nz);
3141     x[i] = sum*v[nz]; /* x[i]=aa[adiag[i]]*sum; v++; */
3142   }
3143 
3144   ierr = PetscLogFlops(2.0*a->nz - A->cmap->n);CHKERRQ(ierr);
3145   ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr);
3146   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
3147   PetscFunctionReturn(0);
3148 }
3149 
3150 PetscErrorCode MatSolve_SeqAIJ(Mat A,Vec bb,Vec xx)
3151 {
3152   Mat_SeqAIJ        *a    = (Mat_SeqAIJ*)A->data;
3153   IS                iscol = a->col,isrow = a->row;
3154   PetscErrorCode    ierr;
3155   PetscInt          i,n=A->rmap->n,*vi,*ai=a->i,*aj=a->j,*adiag = a->diag,nz;
3156   const PetscInt    *rout,*cout,*r,*c;
3157   PetscScalar       *x,*tmp,sum;
3158   const PetscScalar *b;
3159   const MatScalar   *aa = a->a,*v;
3160 
3161   PetscFunctionBegin;
3162   if (!n) PetscFunctionReturn(0);
3163 
3164   ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr);
3165   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
3166   tmp  = a->solve_work;
3167 
3168   ierr = ISGetIndices(isrow,&rout);CHKERRQ(ierr); r = rout;
3169   ierr = ISGetIndices(iscol,&cout);CHKERRQ(ierr); c = cout;
3170 
3171   /* forward solve the lower triangular */
3172   tmp[0] = b[r[0]];
3173   v      = aa;
3174   vi     = aj;
3175   for (i=1; i<n; i++) {
3176     nz  = ai[i+1] - ai[i];
3177     sum = b[r[i]];
3178     PetscSparseDenseMinusDot(sum,tmp,v,vi,nz);
3179     tmp[i] = sum;
3180     v     += nz; vi += nz;
3181   }
3182 
3183   /* backward solve the upper triangular */
3184   for (i=n-1; i>=0; i--) {
3185     v   = aa + adiag[i+1]+1;
3186     vi  = aj + adiag[i+1]+1;
3187     nz  = adiag[i]-adiag[i+1]-1;
3188     sum = tmp[i];
3189     PetscSparseDenseMinusDot(sum,tmp,v,vi,nz);
3190     x[c[i]] = tmp[i] = sum*v[nz]; /* v[nz] = aa[adiag[i]] */
3191   }
3192 
3193   ierr = ISRestoreIndices(isrow,&rout);CHKERRQ(ierr);
3194   ierr = ISRestoreIndices(iscol,&cout);CHKERRQ(ierr);
3195   ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr);
3196   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
3197   ierr = PetscLogFlops(2*a->nz - A->cmap->n);CHKERRQ(ierr);
3198   PetscFunctionReturn(0);
3199 }
3200 
3201 /*
3202     This will get a new name and become a varient of MatILUFactor_SeqAIJ() there is no longer separate functions in the matrix function table for dt factors
3203 */
3204 PetscErrorCode MatILUDTFactor_SeqAIJ(Mat A,IS isrow,IS iscol,const MatFactorInfo *info,Mat *fact)
3205 {
3206   Mat            B = *fact;
3207   Mat_SeqAIJ     *a=(Mat_SeqAIJ*)A->data,*b;
3208   IS             isicol;
3209   PetscErrorCode ierr;
3210   const PetscInt *r,*ic;
3211   PetscInt       i,n=A->rmap->n,*ai=a->i,*aj=a->j,*ajtmp,*adiag;
3212   PetscInt       *bi,*bj,*bdiag,*bdiag_rev;
3213   PetscInt       row,nzi,nzi_bl,nzi_bu,*im,nzi_al,nzi_au;
3214   PetscInt       nlnk,*lnk;
3215   PetscBT        lnkbt;
3216   PetscBool      row_identity,icol_identity;
3217   MatScalar      *aatmp,*pv,*batmp,*ba,*rtmp,*pc,multiplier,*vtmp,diag_tmp;
3218   const PetscInt *ics;
3219   PetscInt       j,nz,*pj,*bjtmp,k,ncut,*jtmp;
3220   PetscReal      dt     =info->dt,shift=info->shiftamount;
3221   PetscInt       dtcount=(PetscInt)info->dtcount,nnz_max;
3222   PetscBool      missing;
3223 
3224   PetscFunctionBegin;
3225   if (dt      == PETSC_DEFAULT) dt = 0.005;
3226   if (dtcount == PETSC_DEFAULT) dtcount = (PetscInt)(1.5*a->rmax);
3227 
3228   /* ------- symbolic factorization, can be reused ---------*/
3229   ierr = MatMissingDiagonal(A,&missing,&i);CHKERRQ(ierr);
3230   if (missing) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Matrix is missing diagonal entry %D",i);
3231   adiag=a->diag;
3232 
3233   ierr = ISInvertPermutation(iscol,PETSC_DECIDE,&isicol);CHKERRQ(ierr);
3234 
3235   /* bdiag is location of diagonal in factor */
3236   ierr = PetscMalloc1(n+1,&bdiag);CHKERRQ(ierr);     /* becomes b->diag */
3237   ierr = PetscMalloc1(n+1,&bdiag_rev);CHKERRQ(ierr); /* temporary */
3238 
3239   /* allocate row pointers bi */
3240   ierr = PetscMalloc1(2*n+2,&bi);CHKERRQ(ierr);
3241 
3242   /* allocate bj and ba; max num of nonzero entries is (ai[n]+2*n*dtcount+2) */
3243   if (dtcount > n-1) dtcount = n-1; /* diagonal is excluded */
3244   nnz_max = ai[n]+2*n*dtcount+2;
3245 
3246   ierr = PetscMalloc1(nnz_max+1,&bj);CHKERRQ(ierr);
3247   ierr = PetscMalloc1(nnz_max+1,&ba);CHKERRQ(ierr);
3248 
3249   /* put together the new matrix */
3250   ierr = MatSeqAIJSetPreallocation_SeqAIJ(B,MAT_SKIP_ALLOCATION,NULL);CHKERRQ(ierr);
3251   ierr = PetscLogObjectParent((PetscObject)B,(PetscObject)isicol);CHKERRQ(ierr);
3252   b    = (Mat_SeqAIJ*)B->data;
3253 
3254   b->free_a       = PETSC_TRUE;
3255   b->free_ij      = PETSC_TRUE;
3256   b->singlemalloc = PETSC_FALSE;
3257 
3258   b->a    = ba;
3259   b->j    = bj;
3260   b->i    = bi;
3261   b->diag = bdiag;
3262   b->ilen = 0;
3263   b->imax = 0;
3264   b->row  = isrow;
3265   b->col  = iscol;
3266   ierr    = PetscObjectReference((PetscObject)isrow);CHKERRQ(ierr);
3267   ierr    = PetscObjectReference((PetscObject)iscol);CHKERRQ(ierr);
3268   b->icol = isicol;
3269 
3270   ierr     = PetscMalloc1(n+1,&b->solve_work);CHKERRQ(ierr);
3271   ierr     = PetscLogObjectMemory((PetscObject)B,nnz_max*(sizeof(PetscInt)+sizeof(MatScalar)));CHKERRQ(ierr);
3272   b->maxnz = nnz_max;
3273 
3274   B->factortype            = MAT_FACTOR_ILUDT;
3275   B->info.factor_mallocs   = 0;
3276   B->info.fill_ratio_given = ((PetscReal)nnz_max)/((PetscReal)ai[n]);
3277   /* ------- end of symbolic factorization ---------*/
3278 
3279   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
3280   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
3281   ics  = ic;
3282 
3283   /* linked list for storing column indices of the active row */
3284   nlnk = n + 1;
3285   ierr = PetscLLCreate(n,n,nlnk,lnk,lnkbt);CHKERRQ(ierr);
3286 
3287   /* im: used by PetscLLAddSortedLU(); jtmp: working array for column indices of active row */
3288   ierr = PetscMalloc2(n,&im,n,&jtmp);CHKERRQ(ierr);
3289   /* rtmp, vtmp: working arrays for sparse and contiguous row entries of active row */
3290   ierr = PetscMalloc2(n,&rtmp,n,&vtmp);CHKERRQ(ierr);
3291   ierr = PetscMemzero(rtmp,n*sizeof(MatScalar));CHKERRQ(ierr);
3292 
3293   bi[0]        = 0;
3294   bdiag[0]     = nnz_max-1; /* location of diag[0] in factor B */
3295   bdiag_rev[n] = bdiag[0];
3296   bi[2*n+1]    = bdiag[0]+1; /* endof bj and ba array */
3297   for (i=0; i<n; i++) {
3298     /* copy initial fill into linked list */
3299     nzi = ai[r[i]+1] - ai[r[i]];
3300     if (!nzi) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_MAT_LU_ZRPVT,"Empty row in matrix: row in original ordering %D in permuted ordering %D",r[i],i);
3301     nzi_al = adiag[r[i]] - ai[r[i]];
3302     nzi_au = ai[r[i]+1] - adiag[r[i]] -1;
3303     ajtmp  = aj + ai[r[i]];
3304     ierr   = PetscLLAddPerm(nzi,ajtmp,ic,n,nlnk,lnk,lnkbt);CHKERRQ(ierr);
3305 
3306     /* load in initial (unfactored row) */
3307     aatmp = a->a + ai[r[i]];
3308     for (j=0; j<nzi; j++) {
3309       rtmp[ics[*ajtmp++]] = *aatmp++;
3310     }
3311 
3312     /* add pivot rows into linked list */
3313     row = lnk[n];
3314     while (row < i) {
3315       nzi_bl = bi[row+1] - bi[row] + 1;
3316       bjtmp  = bj + bdiag[row+1]+1; /* points to 1st column next to the diagonal in U */
3317       ierr   = PetscLLAddSortedLU(bjtmp,row,nlnk,lnk,lnkbt,i,nzi_bl,im);CHKERRQ(ierr);
3318       nzi   += nlnk;
3319       row    = lnk[row];
3320     }
3321 
3322     /* copy data from lnk into jtmp, then initialize lnk */
3323     ierr = PetscLLClean(n,n,nzi,lnk,jtmp,lnkbt);CHKERRQ(ierr);
3324 
3325     /* numerical factorization */
3326     bjtmp = jtmp;
3327     row   = *bjtmp++; /* 1st pivot row */
3328     while (row < i) {
3329       pc         = rtmp + row;
3330       pv         = ba + bdiag[row]; /* 1./(diag of the pivot row) */
3331       multiplier = (*pc) * (*pv);
3332       *pc        = multiplier;
3333       if (PetscAbsScalar(*pc) > dt) { /* apply tolerance dropping rule */
3334         pj = bj + bdiag[row+1] + 1;         /* point to 1st entry of U(row,:) */
3335         pv = ba + bdiag[row+1] + 1;
3336         /* if (multiplier < -1.0 or multiplier >1.0) printf("row/prow %d, %d, multiplier %g\n",i,row,multiplier); */
3337         nz = bdiag[row] - bdiag[row+1] - 1;         /* num of entries in U(row,:), excluding diagonal */
3338         for (j=0; j<nz; j++) rtmp[*pj++] -= multiplier * (*pv++);
3339         ierr = PetscLogFlops(1+2*nz);CHKERRQ(ierr);
3340       }
3341       row = *bjtmp++;
3342     }
3343 
3344     /* copy sparse rtmp into contiguous vtmp; separate L and U part */
3345     diag_tmp = rtmp[i];  /* save diagonal value - may not needed?? */
3346     nzi_bl   = 0; j = 0;
3347     while (jtmp[j] < i) { /* Note: jtmp is sorted */
3348       vtmp[j] = rtmp[jtmp[j]]; rtmp[jtmp[j]]=0.0;
3349       nzi_bl++; j++;
3350     }
3351     nzi_bu = nzi - nzi_bl -1;
3352     while (j < nzi) {
3353       vtmp[j] = rtmp[jtmp[j]]; rtmp[jtmp[j]]=0.0;
3354       j++;
3355     }
3356 
3357     bjtmp = bj + bi[i];
3358     batmp = ba + bi[i];
3359     /* apply level dropping rule to L part */
3360     ncut = nzi_al + dtcount;
3361     if (ncut < nzi_bl) {
3362       ierr = PetscSortSplit(ncut,nzi_bl,vtmp,jtmp);CHKERRQ(ierr);
3363       ierr = PetscSortIntWithScalarArray(ncut,jtmp,vtmp);CHKERRQ(ierr);
3364     } else {
3365       ncut = nzi_bl;
3366     }
3367     for (j=0; j<ncut; j++) {
3368       bjtmp[j] = jtmp[j];
3369       batmp[j] = vtmp[j];
3370       /* printf(" (%d,%g),",bjtmp[j],batmp[j]); */
3371     }
3372     bi[i+1] = bi[i] + ncut;
3373     nzi     = ncut + 1;
3374 
3375     /* apply level dropping rule to U part */
3376     ncut = nzi_au + dtcount;
3377     if (ncut < nzi_bu) {
3378       ierr = PetscSortSplit(ncut,nzi_bu,vtmp+nzi_bl+1,jtmp+nzi_bl+1);CHKERRQ(ierr);
3379       ierr = PetscSortIntWithScalarArray(ncut,jtmp+nzi_bl+1,vtmp+nzi_bl+1);CHKERRQ(ierr);
3380     } else {
3381       ncut = nzi_bu;
3382     }
3383     nzi += ncut;
3384 
3385     /* mark bdiagonal */
3386     bdiag[i+1]       = bdiag[i] - (ncut + 1);
3387     bdiag_rev[n-i-1] = bdiag[i+1];
3388     bi[2*n - i]      = bi[2*n - i +1] - (ncut + 1);
3389     bjtmp            = bj + bdiag[i];
3390     batmp            = ba + bdiag[i];
3391     *bjtmp           = i;
3392     *batmp           = diag_tmp; /* rtmp[i]; */
3393     if (*batmp == 0.0) {
3394       *batmp = dt+shift;
3395       /* printf(" row %d add shift %g\n",i,shift); */
3396     }
3397     *batmp = 1.0/(*batmp); /* invert diagonal entries for simplier triangular solves */
3398     /* printf(" (%d,%g),",*bjtmp,*batmp); */
3399 
3400     bjtmp = bj + bdiag[i+1]+1;
3401     batmp = ba + bdiag[i+1]+1;
3402     for (k=0; k<ncut; k++) {
3403       bjtmp[k] = jtmp[nzi_bl+1+k];
3404       batmp[k] = vtmp[nzi_bl+1+k];
3405       /* printf(" (%d,%g),",bjtmp[k],batmp[k]); */
3406     }
3407     /* printf("\n"); */
3408 
3409     im[i] = nzi;   /* used by PetscLLAddSortedLU() */
3410     /*
3411     printf("row %d: bi %d, bdiag %d\n",i,bi[i],bdiag[i]);
3412     printf(" ----------------------------\n");
3413     */
3414   } /* for (i=0; i<n; i++) */
3415     /* printf("end of L %d, beginning of U %d\n",bi[n],bdiag[n]); */
3416   if (bi[n] >= bdiag[n]) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"end of L array %d cannot >= the beginning of U array %d",bi[n],bdiag[n]);
3417 
3418   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
3419   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
3420 
3421   ierr = PetscLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
3422   ierr = PetscFree2(im,jtmp);CHKERRQ(ierr);
3423   ierr = PetscFree2(rtmp,vtmp);CHKERRQ(ierr);
3424   ierr = PetscFree(bdiag_rev);CHKERRQ(ierr);
3425 
3426   ierr     = PetscLogFlops(B->cmap->n);CHKERRQ(ierr);
3427   b->maxnz = b->nz = bi[n] + bdiag[0] - bdiag[n];
3428 
3429   ierr = ISIdentity(isrow,&row_identity);CHKERRQ(ierr);
3430   ierr = ISIdentity(isicol,&icol_identity);CHKERRQ(ierr);
3431   if (row_identity && icol_identity) {
3432     B->ops->solve = MatSolve_SeqAIJ_NaturalOrdering;
3433   } else {
3434     B->ops->solve = MatSolve_SeqAIJ;
3435   }
3436 
3437   B->ops->solveadd          = 0;
3438   B->ops->solvetranspose    = 0;
3439   B->ops->solvetransposeadd = 0;
3440   B->ops->matsolve          = 0;
3441   B->assembled              = PETSC_TRUE;
3442   B->preallocated           = PETSC_TRUE;
3443   PetscFunctionReturn(0);
3444 }
3445 
3446 /* a wraper of MatILUDTFactor_SeqAIJ() */
3447 /*
3448     This will get a new name and become a varient of MatILUFactor_SeqAIJ() there is no longer separate functions in the matrix function table for dt factors
3449 */
3450 
3451 PetscErrorCode  MatILUDTFactorSymbolic_SeqAIJ(Mat fact,Mat A,IS row,IS col,const MatFactorInfo *info)
3452 {
3453   PetscErrorCode ierr;
3454 
3455   PetscFunctionBegin;
3456   ierr = MatILUDTFactor_SeqAIJ(A,row,col,info,&fact);CHKERRQ(ierr);
3457   PetscFunctionReturn(0);
3458 }
3459 
3460 /*
3461    same as MatLUFactorNumeric_SeqAIJ(), except using contiguous array matrix factors
3462    - intend to replace existing MatLUFactorNumeric_SeqAIJ()
3463 */
3464 /*
3465     This will get a new name and become a varient of MatILUFactor_SeqAIJ() there is no longer separate functions in the matrix function table for dt factors
3466 */
3467 
3468 PetscErrorCode  MatILUDTFactorNumeric_SeqAIJ(Mat fact,Mat A,const MatFactorInfo *info)
3469 {
3470   Mat            C     =fact;
3471   Mat_SeqAIJ     *a    =(Mat_SeqAIJ*)A->data,*b=(Mat_SeqAIJ*)C->data;
3472   IS             isrow = b->row,isicol = b->icol;
3473   PetscErrorCode ierr;
3474   const PetscInt *r,*ic,*ics;
3475   PetscInt       i,j,k,n=A->rmap->n,*ai=a->i,*aj=a->j,*bi=b->i,*bj=b->j;
3476   PetscInt       *ajtmp,*bjtmp,nz,nzl,nzu,row,*bdiag = b->diag,*pj;
3477   MatScalar      *rtmp,*pc,multiplier,*v,*pv,*aa=a->a;
3478   PetscReal      dt=info->dt,shift=info->shiftamount;
3479   PetscBool      row_identity, col_identity;
3480 
3481   PetscFunctionBegin;
3482   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
3483   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
3484   ierr = PetscMalloc1(n+1,&rtmp);CHKERRQ(ierr);
3485   ics  = ic;
3486 
3487   for (i=0; i<n; i++) {
3488     /* initialize rtmp array */
3489     nzl   = bi[i+1] - bi[i];       /* num of nozeros in L(i,:) */
3490     bjtmp = bj + bi[i];
3491     for  (j=0; j<nzl; j++) rtmp[*bjtmp++] = 0.0;
3492     rtmp[i] = 0.0;
3493     nzu     = bdiag[i] - bdiag[i+1]; /* num of nozeros in U(i,:) */
3494     bjtmp   = bj + bdiag[i+1] + 1;
3495     for  (j=0; j<nzu; j++) rtmp[*bjtmp++] = 0.0;
3496 
3497     /* load in initial unfactored row of A */
3498     /* printf("row %d\n",i); */
3499     nz    = ai[r[i]+1] - ai[r[i]];
3500     ajtmp = aj + ai[r[i]];
3501     v     = aa + ai[r[i]];
3502     for (j=0; j<nz; j++) {
3503       rtmp[ics[*ajtmp++]] = v[j];
3504       /* printf(" (%d,%g),",ics[ajtmp[j]],rtmp[ics[ajtmp[j]]]); */
3505     }
3506     /* printf("\n"); */
3507 
3508     /* numerical factorization */
3509     bjtmp = bj + bi[i]; /* point to 1st entry of L(i,:) */
3510     nzl   = bi[i+1] - bi[i]; /* num of entries in L(i,:) */
3511     k     = 0;
3512     while (k < nzl) {
3513       row = *bjtmp++;
3514       /* printf("  prow %d\n",row); */
3515       pc         = rtmp + row;
3516       pv         = b->a + bdiag[row]; /* 1./(diag of the pivot row) */
3517       multiplier = (*pc) * (*pv);
3518       *pc        = multiplier;
3519       if (PetscAbsScalar(multiplier) > dt) {
3520         pj = bj + bdiag[row+1] + 1;         /* point to 1st entry of U(row,:) */
3521         pv = b->a + bdiag[row+1] + 1;
3522         nz = bdiag[row] - bdiag[row+1] - 1;         /* num of entries in U(row,:), excluding diagonal */
3523         for (j=0; j<nz; j++) rtmp[*pj++] -= multiplier * (*pv++);
3524         ierr = PetscLogFlops(1+2*nz);CHKERRQ(ierr);
3525       }
3526       k++;
3527     }
3528 
3529     /* finished row so stick it into b->a */
3530     /* L-part */
3531     pv  = b->a + bi[i];
3532     pj  = bj + bi[i];
3533     nzl = bi[i+1] - bi[i];
3534     for (j=0; j<nzl; j++) {
3535       pv[j] = rtmp[pj[j]];
3536       /* printf(" (%d,%g),",pj[j],pv[j]); */
3537     }
3538 
3539     /* diagonal: invert diagonal entries for simplier triangular solves */
3540     if (rtmp[i] == 0.0) rtmp[i] = dt+shift;
3541     b->a[bdiag[i]] = 1.0/rtmp[i];
3542     /* printf(" (%d,%g),",i,b->a[bdiag[i]]); */
3543 
3544     /* U-part */
3545     pv  = b->a + bdiag[i+1] + 1;
3546     pj  = bj + bdiag[i+1] + 1;
3547     nzu = bdiag[i] - bdiag[i+1] - 1;
3548     for (j=0; j<nzu; j++) {
3549       pv[j] = rtmp[pj[j]];
3550       /* printf(" (%d,%g),",pj[j],pv[j]); */
3551     }
3552     /* printf("\n"); */
3553   }
3554 
3555   ierr = PetscFree(rtmp);CHKERRQ(ierr);
3556   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
3557   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
3558 
3559   ierr = ISIdentity(isrow,&row_identity);CHKERRQ(ierr);
3560   ierr = ISIdentity(isicol,&col_identity);CHKERRQ(ierr);
3561   if (row_identity && col_identity) {
3562     C->ops->solve = MatSolve_SeqAIJ_NaturalOrdering;
3563   } else {
3564     C->ops->solve = MatSolve_SeqAIJ;
3565   }
3566   C->ops->solveadd          = 0;
3567   C->ops->solvetranspose    = 0;
3568   C->ops->solvetransposeadd = 0;
3569   C->ops->matsolve          = 0;
3570   C->assembled              = PETSC_TRUE;
3571   C->preallocated           = PETSC_TRUE;
3572 
3573   ierr = PetscLogFlops(C->cmap->n);CHKERRQ(ierr);
3574   PetscFunctionReturn(0);
3575 }
3576