xref: /petsc/src/mat/impls/baij/seq/baijfact.c (revision 5e71baeff2f3138f93cd4f5927dfd596eb8325cc)
1 
2 /*
3     Factorization code for BAIJ format.
4 */
5 #include <../src/mat/impls/baij/seq/baij.h>
6 #include <petsc/private/kernels/blockinvert.h>
7 
8 PetscErrorCode MatLUFactorNumeric_SeqBAIJ_2(Mat B,Mat A,const MatFactorInfo *info)
9 {
10   Mat            C     =B;
11   Mat_SeqBAIJ    *a    =(Mat_SeqBAIJ*)A->data,*b=(Mat_SeqBAIJ*)C->data;
12   IS             isrow = b->row,isicol = b->icol;
13   PetscErrorCode ierr;
14   const PetscInt *r,*ic;
15   PetscInt       i,j,k,nz,nzL,row,*pj;
16   const PetscInt n=a->mbs,*ai=a->i,*aj=a->j,*bi=b->i,*bj=b->j,bs2=a->bs2;
17   const PetscInt *ajtmp,*bjtmp,*bdiag=b->diag;
18   MatScalar      *rtmp,*pc,*mwork,*pv;
19   MatScalar      *aa=a->a,*v;
20   PetscInt       flg;
21   PetscReal      shift = info->shiftamount;
22   PetscBool      allowzeropivot,zeropivotdetected;
23 
24   PetscFunctionBegin;
25   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
26   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
27   allowzeropivot = PetscNot(A->erroriffailure);
28 
29   /* generate work space needed by the factorization */
30   ierr = PetscMalloc2(bs2*n,&rtmp,bs2,&mwork);CHKERRQ(ierr);
31   ierr = PetscMemzero(rtmp,bs2*n*sizeof(MatScalar));CHKERRQ(ierr);
32 
33   for (i=0; i<n; i++) {
34     /* zero rtmp */
35     /* L part */
36     nz    = bi[i+1] - bi[i];
37     bjtmp = bj + bi[i];
38     for  (j=0; j<nz; j++) {
39       ierr = PetscMemzero(rtmp+bs2*bjtmp[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
40     }
41 
42     /* U part */
43     nz    = bdiag[i] - bdiag[i+1];
44     bjtmp = bj + bdiag[i+1]+1;
45     for  (j=0; j<nz; j++) {
46       ierr = PetscMemzero(rtmp+bs2*bjtmp[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
47     }
48 
49     /* load in initial (unfactored row) */
50     nz    = ai[r[i]+1] - ai[r[i]];
51     ajtmp = aj + ai[r[i]];
52     v     = aa + bs2*ai[r[i]];
53     for (j=0; j<nz; j++) {
54       ierr = PetscMemcpy(rtmp+bs2*ic[ajtmp[j]],v+bs2*j,bs2*sizeof(MatScalar));CHKERRQ(ierr);
55     }
56 
57     /* elimination */
58     bjtmp = bj + bi[i];
59     nzL   = bi[i+1] - bi[i];
60     for (k=0; k < nzL; k++) {
61       row = bjtmp[k];
62       pc  = rtmp + bs2*row;
63       for (flg=0,j=0; j<bs2; j++) {
64         if (pc[j] != (PetscScalar)0.0) {
65           flg = 1;
66           break;
67         }
68       }
69       if (flg) {
70         pv = b->a + bs2*bdiag[row];
71         /* PetscKernel_A_gets_A_times_B(bs,pc,pv,mwork); *pc = *pc * (*pv); */
72         ierr = PetscKernel_A_gets_A_times_B_2(pc,pv,mwork);CHKERRQ(ierr);
73 
74         pj = b->j + bdiag[row+1]+1; /* begining of U(row,:) */
75         pv = b->a + bs2*(bdiag[row+1]+1);
76         nz = bdiag[row] - bdiag[row+1] - 1; /* num of entries inU(row,:), excluding diag */
77         for (j=0; j<nz; j++) {
78           /* PetscKernel_A_gets_A_minus_B_times_C(bs,rtmp+bs2*pj[j],pc,pv+bs2*j); */
79           /* rtmp+bs2*pj[j] = rtmp+bs2*pj[j] - (*pc)*(pv+bs2*j) */
80           v    = rtmp + 4*pj[j];
81           ierr = PetscKernel_A_gets_A_minus_B_times_C_2(v,pc,pv);CHKERRQ(ierr);
82           pv  += 4;
83         }
84         ierr = PetscLogFlops(16*nz+12);CHKERRQ(ierr); /* flops = 2*bs^3*nz + 2*bs^3 - bs2) */
85       }
86     }
87 
88     /* finished row so stick it into b->a */
89     /* L part */
90     pv = b->a + bs2*bi[i];
91     pj = b->j + bi[i];
92     nz = bi[i+1] - bi[i];
93     for (j=0; j<nz; j++) {
94       ierr = PetscMemcpy(pv+bs2*j,rtmp+bs2*pj[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
95     }
96 
97     /* Mark diagonal and invert diagonal for simplier triangular solves */
98     pv   = b->a + bs2*bdiag[i];
99     pj   = b->j + bdiag[i];
100     ierr = PetscMemcpy(pv,rtmp+bs2*pj[0],bs2*sizeof(MatScalar));CHKERRQ(ierr);
101 
102     ierr = PetscKernel_A_gets_inverse_A_2(pv,shift,allowzeropivot,&zeropivotdetected);CHKERRQ(ierr);
103     if (zeropivotdetected) B->factorerrortype = MAT_FACTOR_NUMERIC_ZEROPIVOT;
104 
105     /* U part */
106     pv = b->a + bs2*(bdiag[i+1]+1);
107     pj = b->j + bdiag[i+1]+1;
108     nz = bdiag[i] - bdiag[i+1] - 1;
109     for (j=0; j<nz; j++) {
110       ierr = PetscMemcpy(pv+bs2*j,rtmp+bs2*pj[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
111     }
112   }
113 
114   ierr = PetscFree2(rtmp,mwork);CHKERRQ(ierr);
115   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
116   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
117 
118   C->ops->solve          = MatSolve_SeqBAIJ_2;
119   C->ops->solvetranspose = MatSolveTranspose_SeqBAIJ_2;
120   C->assembled           = PETSC_TRUE;
121 
122   ierr = PetscLogFlops(1.333333333333*2*2*2*n);CHKERRQ(ierr); /* from inverting diagonal blocks */
123   PetscFunctionReturn(0);
124 }
125 
126 PetscErrorCode MatLUFactorNumeric_SeqBAIJ_2_NaturalOrdering(Mat B,Mat A,const MatFactorInfo *info)
127 {
128   Mat            C =B;
129   Mat_SeqBAIJ    *a=(Mat_SeqBAIJ*)A->data,*b=(Mat_SeqBAIJ*)C->data;
130   PetscErrorCode ierr;
131   PetscInt       i,j,k,nz,nzL,row,*pj;
132   const PetscInt n=a->mbs,*ai=a->i,*aj=a->j,*bi=b->i,*bj=b->j,bs2=a->bs2;
133   const PetscInt *ajtmp,*bjtmp,*bdiag=b->diag;
134   MatScalar      *rtmp,*pc,*mwork,*pv;
135   MatScalar      *aa=a->a,*v;
136   PetscInt       flg;
137   PetscReal      shift = info->shiftamount;
138   PetscBool      allowzeropivot,zeropivotdetected;
139 
140   PetscFunctionBegin;
141   allowzeropivot = PetscNot(A->erroriffailure);
142 
143   /* generate work space needed by the factorization */
144   ierr = PetscMalloc2(bs2*n,&rtmp,bs2,&mwork);CHKERRQ(ierr);
145   ierr = PetscMemzero(rtmp,bs2*n*sizeof(MatScalar));CHKERRQ(ierr);
146 
147   for (i=0; i<n; i++) {
148     /* zero rtmp */
149     /* L part */
150     nz    = bi[i+1] - bi[i];
151     bjtmp = bj + bi[i];
152     for  (j=0; j<nz; j++) {
153       ierr = PetscMemzero(rtmp+bs2*bjtmp[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
154     }
155 
156     /* U part */
157     nz    = bdiag[i] - bdiag[i+1];
158     bjtmp = bj + bdiag[i+1]+1;
159     for  (j=0; j<nz; j++) {
160       ierr = PetscMemzero(rtmp+bs2*bjtmp[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
161     }
162 
163     /* load in initial (unfactored row) */
164     nz    = ai[i+1] - ai[i];
165     ajtmp = aj + ai[i];
166     v     = aa + bs2*ai[i];
167     for (j=0; j<nz; j++) {
168       ierr = PetscMemcpy(rtmp+bs2*ajtmp[j],v+bs2*j,bs2*sizeof(MatScalar));CHKERRQ(ierr);
169     }
170 
171     /* elimination */
172     bjtmp = bj + bi[i];
173     nzL   = bi[i+1] - bi[i];
174     for (k=0; k < nzL; k++) {
175       row = bjtmp[k];
176       pc  = rtmp + bs2*row;
177       for (flg=0,j=0; j<bs2; j++) {
178         if (pc[j]!=(PetscScalar)0.0) {
179           flg = 1;
180           break;
181         }
182       }
183       if (flg) {
184         pv = b->a + bs2*bdiag[row];
185         /* PetscKernel_A_gets_A_times_B(bs,pc,pv,mwork); *pc = *pc * (*pv); */
186         ierr = PetscKernel_A_gets_A_times_B_2(pc,pv,mwork);CHKERRQ(ierr);
187 
188         pj = b->j + bdiag[row+1]+1; /* beginning of U(row,:) */
189         pv = b->a + bs2*(bdiag[row+1]+1);
190         nz = bdiag[row]-bdiag[row+1] - 1; /* num of entries in U(row,:) excluding diag */
191         for (j=0; j<nz; j++) {
192           /* PetscKernel_A_gets_A_minus_B_times_C(bs,rtmp+bs2*pj[j],pc,pv+bs2*j); */
193           /* rtmp+bs2*pj[j] = rtmp+bs2*pj[j] - (*pc)*(pv+bs2*j) */
194           v    = rtmp + 4*pj[j];
195           ierr = PetscKernel_A_gets_A_minus_B_times_C_2(v,pc,pv);CHKERRQ(ierr);
196           pv  += 4;
197         }
198         ierr = PetscLogFlops(16*nz+12);CHKERRQ(ierr); /* flops = 2*bs^3*nz + 2*bs^3 - bs2) */
199       }
200     }
201 
202     /* finished row so stick it into b->a */
203     /* L part */
204     pv = b->a + bs2*bi[i];
205     pj = b->j + bi[i];
206     nz = bi[i+1] - bi[i];
207     for (j=0; j<nz; j++) {
208       ierr = PetscMemcpy(pv+bs2*j,rtmp+bs2*pj[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
209     }
210 
211     /* Mark diagonal and invert diagonal for simplier triangular solves */
212     pv   = b->a + bs2*bdiag[i];
213     pj   = b->j + bdiag[i];
214     ierr = PetscMemcpy(pv,rtmp+bs2*pj[0],bs2*sizeof(MatScalar));CHKERRQ(ierr);
215 
216     ierr = PetscKernel_A_gets_inverse_A_2(pv,shift,allowzeropivot,&zeropivotdetected);CHKERRQ(ierr);
217     if (zeropivotdetected) B->factorerrortype = MAT_FACTOR_NUMERIC_ZEROPIVOT;
218 
219     /* U part */
220     /*
221     pv = b->a + bs2*bi[2*n-i];
222     pj = b->j + bi[2*n-i];
223     nz = bi[2*n-i+1] - bi[2*n-i] - 1;
224     */
225     pv = b->a + bs2*(bdiag[i+1]+1);
226     pj = b->j + bdiag[i+1]+1;
227     nz = bdiag[i] - bdiag[i+1] - 1;
228     for (j=0; j<nz; j++) {
229       ierr = PetscMemcpy(pv+bs2*j,rtmp+bs2*pj[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
230     }
231   }
232   ierr = PetscFree2(rtmp,mwork);CHKERRQ(ierr);
233 
234   C->ops->solve          = MatSolve_SeqBAIJ_2_NaturalOrdering;
235   C->ops->forwardsolve   = MatForwardSolve_SeqBAIJ_2_NaturalOrdering;
236   C->ops->backwardsolve  = MatBackwardSolve_SeqBAIJ_2_NaturalOrdering;
237   C->ops->solvetranspose = MatSolveTranspose_SeqBAIJ_2_NaturalOrdering;
238   C->assembled           = PETSC_TRUE;
239 
240   ierr = PetscLogFlops(1.333333333333*2*2*2*n);CHKERRQ(ierr); /* from inverting diagonal blocks */
241   PetscFunctionReturn(0);
242 }
243 
244 PetscErrorCode MatLUFactorNumeric_SeqBAIJ_2_inplace(Mat B,Mat A,const MatFactorInfo *info)
245 {
246   Mat            C     = B;
247   Mat_SeqBAIJ    *a    = (Mat_SeqBAIJ*)A->data,*b = (Mat_SeqBAIJ*)C->data;
248   IS             isrow = b->row,isicol = b->icol;
249   PetscErrorCode ierr;
250   const PetscInt *r,*ic;
251   PetscInt       i,j,n = a->mbs,*bi = b->i,*bj = b->j;
252   PetscInt       *ajtmpold,*ajtmp,nz,row;
253   PetscInt       *diag_offset=b->diag,idx,*ai=a->i,*aj=a->j,*pj;
254   MatScalar      *pv,*v,*rtmp,m1,m2,m3,m4,*pc,*w,*x,x1,x2,x3,x4;
255   MatScalar      p1,p2,p3,p4;
256   MatScalar      *ba   = b->a,*aa = a->a;
257   PetscReal      shift = info->shiftamount;
258   PetscBool      allowzeropivot,zeropivotdetected;
259 
260   PetscFunctionBegin;
261   allowzeropivot = PetscNot(A->erroriffailure);
262   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
263   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
264   ierr = PetscMalloc1(4*(n+1),&rtmp);CHKERRQ(ierr);
265 
266   for (i=0; i<n; i++) {
267     nz    = bi[i+1] - bi[i];
268     ajtmp = bj + bi[i];
269     for  (j=0; j<nz; j++) {
270       x = rtmp+4*ajtmp[j]; x[0] = x[1] = x[2] = x[3] = 0.0;
271     }
272     /* load in initial (unfactored row) */
273     idx      = r[i];
274     nz       = ai[idx+1] - ai[idx];
275     ajtmpold = aj + ai[idx];
276     v        = aa + 4*ai[idx];
277     for (j=0; j<nz; j++) {
278       x    = rtmp+4*ic[ajtmpold[j]];
279       x[0] = v[0]; x[1] = v[1]; x[2] = v[2]; x[3] = v[3];
280       v   += 4;
281     }
282     row = *ajtmp++;
283     while (row < i) {
284       pc = rtmp + 4*row;
285       p1 = pc[0]; p2 = pc[1]; p3 = pc[2]; p4 = pc[3];
286       if (p1 != (PetscScalar)0.0 || p2 != (PetscScalar)0.0 || p3 != (PetscScalar)0.0 || p4 != (PetscScalar)0.0) {
287         pv    = ba + 4*diag_offset[row];
288         pj    = bj + diag_offset[row] + 1;
289         x1    = pv[0]; x2 = pv[1]; x3 = pv[2]; x4 = pv[3];
290         pc[0] = m1 = p1*x1 + p3*x2;
291         pc[1] = m2 = p2*x1 + p4*x2;
292         pc[2] = m3 = p1*x3 + p3*x4;
293         pc[3] = m4 = p2*x3 + p4*x4;
294         nz    = bi[row+1] - diag_offset[row] - 1;
295         pv   += 4;
296         for (j=0; j<nz; j++) {
297           x1    = pv[0]; x2 = pv[1]; x3 = pv[2]; x4 = pv[3];
298           x     = rtmp + 4*pj[j];
299           x[0] -= m1*x1 + m3*x2;
300           x[1] -= m2*x1 + m4*x2;
301           x[2] -= m1*x3 + m3*x4;
302           x[3] -= m2*x3 + m4*x4;
303           pv   += 4;
304         }
305         ierr = PetscLogFlops(16.0*nz+12.0);CHKERRQ(ierr);
306       }
307       row = *ajtmp++;
308     }
309     /* finished row so stick it into b->a */
310     pv = ba + 4*bi[i];
311     pj = bj + bi[i];
312     nz = bi[i+1] - bi[i];
313     for (j=0; j<nz; j++) {
314       x     = rtmp+4*pj[j];
315       pv[0] = x[0]; pv[1] = x[1]; pv[2] = x[2]; pv[3] = x[3];
316       pv   += 4;
317     }
318     /* invert diagonal block */
319     w    = ba + 4*diag_offset[i];
320     ierr = PetscKernel_A_gets_inverse_A_2(w,shift,allowzeropivot,&zeropivotdetected);CHKERRQ(ierr);
321     if (zeropivotdetected) C->factorerrortype = MAT_FACTOR_NUMERIC_ZEROPIVOT;
322   }
323 
324   ierr = PetscFree(rtmp);CHKERRQ(ierr);
325   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
326   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
327 
328   C->ops->solve          = MatSolve_SeqBAIJ_2_inplace;
329   C->ops->solvetranspose = MatSolveTranspose_SeqBAIJ_2_inplace;
330   C->assembled           = PETSC_TRUE;
331 
332   ierr = PetscLogFlops(1.333333333333*8*b->mbs);CHKERRQ(ierr); /* from inverting diagonal blocks */
333   PetscFunctionReturn(0);
334 }
335 /*
336       Version for when blocks are 2 by 2 Using natural ordering
337 */
338 PetscErrorCode MatLUFactorNumeric_SeqBAIJ_2_NaturalOrdering_inplace(Mat C,Mat A,const MatFactorInfo *info)
339 {
340   Mat_SeqBAIJ    *a = (Mat_SeqBAIJ*)A->data,*b = (Mat_SeqBAIJ*)C->data;
341   PetscErrorCode ierr;
342   PetscInt       i,j,n = a->mbs,*bi = b->i,*bj = b->j;
343   PetscInt       *ajtmpold,*ajtmp,nz,row;
344   PetscInt       *diag_offset = b->diag,*ai=a->i,*aj=a->j,*pj;
345   MatScalar      *pv,*v,*rtmp,*pc,*w,*x;
346   MatScalar      p1,p2,p3,p4,m1,m2,m3,m4,x1,x2,x3,x4;
347   MatScalar      *ba   = b->a,*aa = a->a;
348   PetscReal      shift = info->shiftamount;
349   PetscBool      allowzeropivot,zeropivotdetected;
350 
351   PetscFunctionBegin;
352   allowzeropivot = PetscNot(A->erroriffailure);
353   ierr = PetscMalloc1(4*(n+1),&rtmp);CHKERRQ(ierr);
354   for (i=0; i<n; i++) {
355     nz    = bi[i+1] - bi[i];
356     ajtmp = bj + bi[i];
357     for  (j=0; j<nz; j++) {
358       x    = rtmp+4*ajtmp[j];
359       x[0] = x[1]  = x[2]  = x[3]  = 0.0;
360     }
361     /* load in initial (unfactored row) */
362     nz       = ai[i+1] - ai[i];
363     ajtmpold = aj + ai[i];
364     v        = aa + 4*ai[i];
365     for (j=0; j<nz; j++) {
366       x    = rtmp+4*ajtmpold[j];
367       x[0] = v[0];  x[1]  = v[1];  x[2]  = v[2];  x[3]  = v[3];
368       v   += 4;
369     }
370     row = *ajtmp++;
371     while (row < i) {
372       pc = rtmp + 4*row;
373       p1 = pc[0];  p2  = pc[1];  p3  = pc[2];  p4  = pc[3];
374       if (p1 != (PetscScalar)0.0 || p2 != (PetscScalar)0.0 || p3 != (PetscScalar)0.0 || p4 != (PetscScalar)0.0) {
375         pv    = ba + 4*diag_offset[row];
376         pj    = bj + diag_offset[row] + 1;
377         x1    = pv[0];  x2  = pv[1];  x3  = pv[2];  x4  = pv[3];
378         pc[0] = m1 = p1*x1 + p3*x2;
379         pc[1] = m2 = p2*x1 + p4*x2;
380         pc[2] = m3 = p1*x3 + p3*x4;
381         pc[3] = m4 = p2*x3 + p4*x4;
382         nz    = bi[row+1] - diag_offset[row] - 1;
383         pv   += 4;
384         for (j=0; j<nz; j++) {
385           x1    = pv[0];  x2  = pv[1];   x3 = pv[2];  x4  = pv[3];
386           x     = rtmp + 4*pj[j];
387           x[0] -= m1*x1 + m3*x2;
388           x[1] -= m2*x1 + m4*x2;
389           x[2] -= m1*x3 + m3*x4;
390           x[3] -= m2*x3 + m4*x4;
391           pv   += 4;
392         }
393         ierr = PetscLogFlops(16.0*nz+12.0);CHKERRQ(ierr);
394       }
395       row = *ajtmp++;
396     }
397     /* finished row so stick it into b->a */
398     pv = ba + 4*bi[i];
399     pj = bj + bi[i];
400     nz = bi[i+1] - bi[i];
401     for (j=0; j<nz; j++) {
402       x     = rtmp+4*pj[j];
403       pv[0] = x[0];  pv[1]  = x[1];  pv[2]  = x[2];  pv[3]  = x[3];
404       /*
405       printf(" col %d:",pj[j]);
406       PetscInt j1;
407       for (j1=0; j1<4; j1++) printf(" %g,",*(pv+j1));
408       printf("\n");
409       */
410       pv += 4;
411     }
412     /* invert diagonal block */
413     w = ba + 4*diag_offset[i];
414     ierr = PetscKernel_A_gets_inverse_A_2(w,shift, allowzeropivot,&zeropivotdetected);CHKERRQ(ierr);
415     if (zeropivotdetected) C->factorerrortype = MAT_FACTOR_NUMERIC_ZEROPIVOT;
416   }
417 
418   ierr = PetscFree(rtmp);CHKERRQ(ierr);
419 
420   C->ops->solve          = MatSolve_SeqBAIJ_2_NaturalOrdering_inplace;
421   C->ops->solvetranspose = MatSolveTranspose_SeqBAIJ_2_NaturalOrdering_inplace;
422   C->assembled           = PETSC_TRUE;
423 
424   ierr = PetscLogFlops(1.333333333333*8*b->mbs);CHKERRQ(ierr); /* from inverting diagonal blocks */
425   PetscFunctionReturn(0);
426 }
427 
428 /* ----------------------------------------------------------- */
429 /*
430      Version for when blocks are 1 by 1.
431 */
432 PetscErrorCode MatLUFactorNumeric_SeqBAIJ_1(Mat B,Mat A,const MatFactorInfo *info)
433 {
434   Mat             C     =B;
435   Mat_SeqBAIJ     *a    =(Mat_SeqBAIJ*)A->data,*b=(Mat_SeqBAIJ*)C->data;
436   IS              isrow = b->row,isicol = b->icol;
437   PetscErrorCode  ierr;
438   const PetscInt  *r,*ic,*ics;
439   const PetscInt  n=a->mbs,*ai=a->i,*aj=a->j,*bi=b->i,*bj=b->j,*bdiag=b->diag;
440   PetscInt        i,j,k,nz,nzL,row,*pj;
441   const PetscInt  *ajtmp,*bjtmp;
442   MatScalar       *rtmp,*pc,multiplier,*pv;
443   const MatScalar *aa=a->a,*v;
444   PetscBool       row_identity,col_identity;
445   FactorShiftCtx  sctx;
446   const PetscInt  *ddiag;
447   PetscReal       rs;
448   MatScalar       d;
449 
450   PetscFunctionBegin;
451   /* MatPivotSetUp(): initialize shift context sctx */
452   ierr = PetscMemzero(&sctx,sizeof(FactorShiftCtx));CHKERRQ(ierr);
453 
454   if (info->shifttype == (PetscReal) MAT_SHIFT_POSITIVE_DEFINITE) { /* set sctx.shift_top=max{rs} */
455     ddiag          = a->diag;
456     sctx.shift_top = info->zeropivot;
457     for (i=0; i<n; i++) {
458       /* calculate sum(|aij|)-RealPart(aii), amt of shift needed for this row */
459       d  = (aa)[ddiag[i]];
460       rs = -PetscAbsScalar(d) - PetscRealPart(d);
461       v  = aa+ai[i];
462       nz = ai[i+1] - ai[i];
463       for (j=0; j<nz; j++) rs += PetscAbsScalar(v[j]);
464       if (rs>sctx.shift_top) sctx.shift_top = rs;
465     }
466     sctx.shift_top *= 1.1;
467     sctx.nshift_max = 5;
468     sctx.shift_lo   = 0.;
469     sctx.shift_hi   = 1.;
470   }
471 
472   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
473   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
474   ierr = PetscMalloc1(n+1,&rtmp);CHKERRQ(ierr);
475   ics  = ic;
476 
477   do {
478     sctx.newshift = PETSC_FALSE;
479     for (i=0; i<n; i++) {
480       /* zero rtmp */
481       /* L part */
482       nz    = bi[i+1] - bi[i];
483       bjtmp = bj + bi[i];
484       for  (j=0; j<nz; j++) rtmp[bjtmp[j]] = 0.0;
485 
486       /* U part */
487       nz    = bdiag[i]-bdiag[i+1];
488       bjtmp = bj + bdiag[i+1]+1;
489       for  (j=0; j<nz; j++) rtmp[bjtmp[j]] = 0.0;
490 
491       /* load in initial (unfactored row) */
492       nz    = ai[r[i]+1] - ai[r[i]];
493       ajtmp = aj + ai[r[i]];
494       v     = aa + ai[r[i]];
495       for (j=0; j<nz; j++) rtmp[ics[ajtmp[j]]] = v[j];
496 
497       /* ZeropivotApply() */
498       rtmp[i] += sctx.shift_amount;  /* shift the diagonal of the matrix */
499 
500       /* elimination */
501       bjtmp = bj + bi[i];
502       row   = *bjtmp++;
503       nzL   = bi[i+1] - bi[i];
504       for (k=0; k < nzL; k++) {
505         pc = rtmp + row;
506         if (*pc != (PetscScalar)0.0) {
507           pv         = b->a + bdiag[row];
508           multiplier = *pc * (*pv);
509           *pc        = multiplier;
510 
511           pj = b->j + bdiag[row+1]+1; /* beginning of U(row,:) */
512           pv = b->a + bdiag[row+1]+1;
513           nz = bdiag[row]-bdiag[row+1]-1; /* num of entries in U(row,:) excluding diag */
514           for (j=0; j<nz; j++) rtmp[pj[j]] -= multiplier * pv[j];
515           ierr = PetscLogFlops(2.0*nz);CHKERRQ(ierr);
516         }
517         row = *bjtmp++;
518       }
519 
520       /* finished row so stick it into b->a */
521       rs = 0.0;
522       /* L part */
523       pv = b->a + bi[i];
524       pj = b->j + bi[i];
525       nz = bi[i+1] - bi[i];
526       for (j=0; j<nz; j++) {
527         pv[j] = rtmp[pj[j]]; rs += PetscAbsScalar(pv[j]);
528       }
529 
530       /* U part */
531       pv = b->a + bdiag[i+1]+1;
532       pj = b->j + bdiag[i+1]+1;
533       nz = bdiag[i] - bdiag[i+1]-1;
534       for (j=0; j<nz; j++) {
535         pv[j] = rtmp[pj[j]]; rs += PetscAbsScalar(pv[j]);
536       }
537 
538       sctx.rs = rs;
539       sctx.pv = rtmp[i];
540       ierr    = MatPivotCheck(B,A,info,&sctx,i);CHKERRQ(ierr);
541       if (sctx.newshift) break; /* break for-loop */
542       rtmp[i] = sctx.pv; /* sctx.pv might be updated in the case of MAT_SHIFT_INBLOCKS */
543 
544       /* Mark diagonal and invert diagonal for simplier triangular solves */
545       pv  = b->a + bdiag[i];
546       *pv = (PetscScalar)1.0/rtmp[i];
547 
548     } /* endof for (i=0; i<n; i++) { */
549 
550     /* MatPivotRefine() */
551     if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE && !sctx.newshift && sctx.shift_fraction>0 && sctx.nshift<sctx.nshift_max) {
552       /*
553        * if no shift in this attempt & shifting & started shifting & can refine,
554        * then try lower shift
555        */
556       sctx.shift_hi       = sctx.shift_fraction;
557       sctx.shift_fraction = (sctx.shift_hi+sctx.shift_lo)/2.;
558       sctx.shift_amount   = sctx.shift_fraction * sctx.shift_top;
559       sctx.newshift       = PETSC_TRUE;
560       sctx.nshift++;
561     }
562   } while (sctx.newshift);
563 
564   ierr = PetscFree(rtmp);CHKERRQ(ierr);
565   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
566   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
567 
568   ierr = ISIdentity(isrow,&row_identity);CHKERRQ(ierr);
569   ierr = ISIdentity(isicol,&col_identity);CHKERRQ(ierr);
570   if (row_identity && col_identity) {
571     C->ops->solve          = MatSolve_SeqBAIJ_1_NaturalOrdering;
572     C->ops->forwardsolve   = MatForwardSolve_SeqBAIJ_1_NaturalOrdering;
573     C->ops->backwardsolve  = MatBackwardSolve_SeqBAIJ_1_NaturalOrdering;
574     C->ops->solvetranspose = MatSolveTranspose_SeqBAIJ_1_NaturalOrdering;
575   } else {
576     C->ops->solve          = MatSolve_SeqBAIJ_1;
577     C->ops->solvetranspose = MatSolveTranspose_SeqBAIJ_1;
578   }
579   C->assembled = PETSC_TRUE;
580   ierr         = PetscLogFlops(C->cmap->n);CHKERRQ(ierr);
581 
582   /* MatShiftView(A,info,&sctx) */
583   if (sctx.nshift) {
584     if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE) {
585       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);
586     } else if (info->shifttype == (PetscReal)MAT_SHIFT_NONZERO) {
587       ierr = PetscInfo2(A,"number of shift_nz tries %D, shift_amount %g\n",sctx.nshift,(double)sctx.shift_amount);CHKERRQ(ierr);
588     } else if (info->shifttype == (PetscReal)MAT_SHIFT_INBLOCKS) {
589       ierr = PetscInfo2(A,"number of shift_inblocks applied %D, each shift_amount %g\n",sctx.nshift,(double)info->shiftamount);CHKERRQ(ierr);
590     }
591   }
592   PetscFunctionReturn(0);
593 }
594 
595 PetscErrorCode MatLUFactorNumeric_SeqBAIJ_1_inplace(Mat C,Mat A,const MatFactorInfo *info)
596 {
597   Mat_SeqBAIJ    *a    = (Mat_SeqBAIJ*)A->data,*b = (Mat_SeqBAIJ*)C->data;
598   IS             isrow = b->row,isicol = b->icol;
599   PetscErrorCode ierr;
600   const PetscInt *r,*ic;
601   PetscInt       i,j,n = a->mbs,*bi = b->i,*bj = b->j;
602   PetscInt       *ajtmpold,*ajtmp,nz,row,*ai = a->i,*aj = a->j;
603   PetscInt       *diag_offset = b->diag,diag,*pj;
604   MatScalar      *pv,*v,*rtmp,multiplier,*pc;
605   MatScalar      *ba = b->a,*aa = a->a;
606   PetscBool      row_identity, col_identity;
607 
608   PetscFunctionBegin;
609   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
610   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
611   ierr = PetscMalloc1(n+1,&rtmp);CHKERRQ(ierr);
612 
613   for (i=0; i<n; i++) {
614     nz    = bi[i+1] - bi[i];
615     ajtmp = bj + bi[i];
616     for  (j=0; j<nz; j++) rtmp[ajtmp[j]] = 0.0;
617 
618     /* load in initial (unfactored row) */
619     nz       = ai[r[i]+1] - ai[r[i]];
620     ajtmpold = aj + ai[r[i]];
621     v        = aa + ai[r[i]];
622     for (j=0; j<nz; j++) rtmp[ic[ajtmpold[j]]] =  v[j];
623 
624     row = *ajtmp++;
625     while (row < i) {
626       pc = rtmp + row;
627       if (*pc != 0.0) {
628         pv         = ba + diag_offset[row];
629         pj         = bj + diag_offset[row] + 1;
630         multiplier = *pc * *pv++;
631         *pc        = multiplier;
632         nz         = bi[row+1] - diag_offset[row] - 1;
633         for (j=0; j<nz; j++) rtmp[pj[j]] -= multiplier * pv[j];
634         ierr = PetscLogFlops(1.0+2.0*nz);CHKERRQ(ierr);
635       }
636       row = *ajtmp++;
637     }
638     /* finished row so stick it into b->a */
639     pv = ba + bi[i];
640     pj = bj + bi[i];
641     nz = bi[i+1] - bi[i];
642     for (j=0; j<nz; j++) pv[j] = rtmp[pj[j]];
643     diag = diag_offset[i] - bi[i];
644     /* check pivot entry for current row */
645     if (pv[diag] == 0.0) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_MAT_LU_ZRPVT,"Zero pivot: row in original ordering %D in permuted ordering %D",r[i],i);
646     pv[diag] = 1.0/pv[diag];
647   }
648 
649   ierr = PetscFree(rtmp);CHKERRQ(ierr);
650   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
651   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
652   ierr = ISIdentity(isrow,&row_identity);CHKERRQ(ierr);
653   ierr = ISIdentity(isicol,&col_identity);CHKERRQ(ierr);
654   if (row_identity && col_identity) {
655     C->ops->solve          = MatSolve_SeqBAIJ_1_NaturalOrdering_inplace;
656     C->ops->solvetranspose = MatSolveTranspose_SeqBAIJ_1_NaturalOrdering_inplace;
657   } else {
658     C->ops->solve          = MatSolve_SeqBAIJ_1_inplace;
659     C->ops->solvetranspose = MatSolveTranspose_SeqBAIJ_1_inplace;
660   }
661   C->assembled = PETSC_TRUE;
662   ierr         = PetscLogFlops(C->cmap->n);CHKERRQ(ierr);
663   PetscFunctionReturn(0);
664 }
665 
666 PETSC_INTERN PetscErrorCode MatGetFactor_seqbaij_petsc(Mat A,const MatFactorType ftype,Mat *B)
667 {
668   PetscInt       n = A->rmap->n;
669   PetscErrorCode ierr;
670 
671   PetscFunctionBegin;
672 #if defined(PETSC_USE_COMPLEX)
673   if (A->hermitian && (ftype == MAT_FACTOR_CHOLESKY || ftype == MAT_FACTOR_ICC)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Hermitian Factor is not supported");
674 #endif
675   ierr = MatCreate(PetscObjectComm((PetscObject)A),B);CHKERRQ(ierr);
676   ierr = MatSetSizes(*B,n,n,n,n);CHKERRQ(ierr);
677   if (ftype == MAT_FACTOR_LU || ftype == MAT_FACTOR_ILU || ftype == MAT_FACTOR_ILUDT) {
678     ierr = MatSetType(*B,MATSEQBAIJ);CHKERRQ(ierr);
679 
680     (*B)->ops->lufactorsymbolic  = MatLUFactorSymbolic_SeqBAIJ;
681     (*B)->ops->ilufactorsymbolic = MatILUFactorSymbolic_SeqBAIJ;
682   } else if (ftype == MAT_FACTOR_CHOLESKY || ftype == MAT_FACTOR_ICC) {
683     ierr = MatSetType(*B,MATSEQSBAIJ);CHKERRQ(ierr);
684     ierr = MatSeqSBAIJSetPreallocation(*B,A->rmap->bs,MAT_SKIP_ALLOCATION,NULL);CHKERRQ(ierr);
685 
686     (*B)->ops->iccfactorsymbolic      = MatICCFactorSymbolic_SeqBAIJ;
687     (*B)->ops->choleskyfactorsymbolic = MatCholeskyFactorSymbolic_SeqBAIJ;
688   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Factor type not supported");
689   (*B)->factortype = ftype;
690 
691   ierr = PetscFree((*B)->solvertype);CHKERRQ(ierr);
692   ierr = PetscStrallocpy(MATSOLVERPETSC,&(*B)->solvertype);CHKERRQ(ierr);
693   PetscFunctionReturn(0);
694 }
695 
696 /* ----------------------------------------------------------- */
697 PetscErrorCode MatLUFactor_SeqBAIJ(Mat A,IS row,IS col,const MatFactorInfo *info)
698 {
699   PetscErrorCode ierr;
700   Mat            C;
701 
702   PetscFunctionBegin;
703   ierr = MatGetFactor(A,MATSOLVERPETSC,MAT_FACTOR_LU,&C);CHKERRQ(ierr);
704   ierr = MatLUFactorSymbolic(C,A,row,col,info);CHKERRQ(ierr);
705   ierr = MatLUFactorNumeric(C,A,info);CHKERRQ(ierr);
706 
707   A->ops->solve          = C->ops->solve;
708   A->ops->solvetranspose = C->ops->solvetranspose;
709 
710   ierr = MatHeaderMerge(A,&C);CHKERRQ(ierr);
711   ierr = PetscLogObjectParent((PetscObject)A,(PetscObject)((Mat_SeqBAIJ*)(A->data))->icol);CHKERRQ(ierr);
712   PetscFunctionReturn(0);
713 }
714 
715 #include <../src/mat/impls/sbaij/seq/sbaij.h>
716 PetscErrorCode MatCholeskyFactorNumeric_SeqBAIJ_N(Mat C,Mat A,const MatFactorInfo *info)
717 {
718   PetscErrorCode ierr;
719   Mat_SeqBAIJ    *a=(Mat_SeqBAIJ*)A->data;
720   Mat_SeqSBAIJ   *b=(Mat_SeqSBAIJ*)C->data;
721   IS             ip=b->row;
722   const PetscInt *rip;
723   PetscInt       i,j,mbs=a->mbs,bs=A->rmap->bs,*bi=b->i,*bj=b->j,*bcol;
724   PetscInt       *ai=a->i,*aj=a->j;
725   PetscInt       k,jmin,jmax,*jl,*il,col,nexti,ili,nz;
726   MatScalar      *rtmp,*ba=b->a,*bval,*aa=a->a,dk,uikdi;
727   PetscReal      rs;
728   FactorShiftCtx sctx;
729 
730   PetscFunctionBegin;
731   if (bs > 1) { /* convert A to a SBAIJ matrix and apply Cholesky factorization from it */
732     if (!a->sbaijMat) {
733       ierr = MatConvert(A,MATSEQSBAIJ,MAT_INITIAL_MATRIX,&a->sbaijMat);CHKERRQ(ierr);
734     }
735     ierr = (a->sbaijMat)->ops->choleskyfactornumeric(C,a->sbaijMat,info);CHKERRQ(ierr);
736     ierr = MatDestroy(&a->sbaijMat);CHKERRQ(ierr);
737     PetscFunctionReturn(0);
738   }
739 
740   /* MatPivotSetUp(): initialize shift context sctx */
741   ierr = PetscMemzero(&sctx,sizeof(FactorShiftCtx));CHKERRQ(ierr);
742 
743   ierr = ISGetIndices(ip,&rip);CHKERRQ(ierr);
744   ierr = PetscMalloc3(mbs,&rtmp,mbs,&il,mbs,&jl);CHKERRQ(ierr);
745 
746   sctx.shift_amount = 0.;
747   sctx.nshift       = 0;
748   do {
749     sctx.newshift = PETSC_FALSE;
750     for (i=0; i<mbs; i++) {
751       rtmp[i] = 0.0; jl[i] = mbs; il[0] = 0;
752     }
753 
754     for (k = 0; k<mbs; k++) {
755       bval = ba + bi[k];
756       /* initialize k-th row by the perm[k]-th row of A */
757       jmin = ai[rip[k]]; jmax = ai[rip[k]+1];
758       for (j = jmin; j < jmax; j++) {
759         col = rip[aj[j]];
760         if (col >= k) { /* only take upper triangular entry */
761           rtmp[col] = aa[j];
762           *bval++   = 0.0; /* for in-place factorization */
763         }
764       }
765 
766       /* shift the diagonal of the matrix */
767       if (sctx.nshift) rtmp[k] += sctx.shift_amount;
768 
769       /* modify k-th row by adding in those rows i with U(i,k)!=0 */
770       dk = rtmp[k];
771       i  = jl[k]; /* first row to be added to k_th row  */
772 
773       while (i < k) {
774         nexti = jl[i]; /* next row to be added to k_th row */
775 
776         /* compute multiplier, update diag(k) and U(i,k) */
777         ili     = il[i]; /* index of first nonzero element in U(i,k:bms-1) */
778         uikdi   = -ba[ili]*ba[bi[i]]; /* diagonal(k) */
779         dk     += uikdi*ba[ili];
780         ba[ili] = uikdi; /* -U(i,k) */
781 
782         /* add multiple of row i to k-th row */
783         jmin = ili + 1; jmax = bi[i+1];
784         if (jmin < jmax) {
785           for (j=jmin; j<jmax; j++) rtmp[bj[j]] += uikdi*ba[j];
786           /* update il and jl for row i */
787           il[i] = jmin;
788           j     = bj[jmin]; jl[i] = jl[j]; jl[j] = i;
789         }
790         i = nexti;
791       }
792 
793       /* shift the diagonals when zero pivot is detected */
794       /* compute rs=sum of abs(off-diagonal) */
795       rs   = 0.0;
796       jmin = bi[k]+1;
797       nz   = bi[k+1] - jmin;
798       if (nz) {
799         bcol = bj + jmin;
800         while (nz--) {
801           rs += PetscAbsScalar(rtmp[*bcol]);
802           bcol++;
803         }
804       }
805 
806       sctx.rs = rs;
807       sctx.pv = dk;
808       ierr    = MatPivotCheck(C,A,info,&sctx,k);CHKERRQ(ierr);
809       if (sctx.newshift) break;
810       dk = sctx.pv;
811 
812       /* copy data into U(k,:) */
813       ba[bi[k]] = 1.0/dk; /* U(k,k) */
814       jmin      = bi[k]+1; jmax = bi[k+1];
815       if (jmin < jmax) {
816         for (j=jmin; j<jmax; j++) {
817           col = bj[j]; ba[j] = rtmp[col]; rtmp[col] = 0.0;
818         }
819         /* add the k-th row into il and jl */
820         il[k] = jmin;
821         i     = bj[jmin]; jl[k] = jl[i]; jl[i] = k;
822       }
823     }
824   } while (sctx.newshift);
825   ierr = PetscFree3(rtmp,il,jl);CHKERRQ(ierr);
826 
827   ierr = ISRestoreIndices(ip,&rip);CHKERRQ(ierr);
828 
829   C->assembled    = PETSC_TRUE;
830   C->preallocated = PETSC_TRUE;
831 
832   ierr = PetscLogFlops(C->rmap->N);CHKERRQ(ierr);
833   if (sctx.nshift) {
834     if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE) {
835       ierr = PetscInfo2(A,"number of shiftpd tries %D, shift_amount %g\n",sctx.nshift,(double)sctx.shift_amount);CHKERRQ(ierr);
836     } else if (info->shifttype == (PetscReal)MAT_SHIFT_NONZERO) {
837       ierr = PetscInfo2(A,"number of shiftnz tries %D, shift_amount %g\n",sctx.nshift,(double)sctx.shift_amount);CHKERRQ(ierr);
838     }
839   }
840   PetscFunctionReturn(0);
841 }
842 
843 PetscErrorCode MatCholeskyFactorNumeric_SeqBAIJ_N_NaturalOrdering(Mat C,Mat A,const MatFactorInfo *info)
844 {
845   Mat_SeqBAIJ    *a=(Mat_SeqBAIJ*)A->data;
846   Mat_SeqSBAIJ   *b=(Mat_SeqSBAIJ*)C->data;
847   PetscErrorCode ierr;
848   PetscInt       i,j,am=a->mbs;
849   PetscInt       *ai=a->i,*aj=a->j,*bi=b->i,*bj=b->j;
850   PetscInt       k,jmin,*jl,*il,nexti,ili,*acol,*bcol,nz;
851   MatScalar      *rtmp,*ba=b->a,*aa=a->a,dk,uikdi,*aval,*bval;
852   PetscReal      rs;
853   FactorShiftCtx sctx;
854 
855   PetscFunctionBegin;
856   /* MatPivotSetUp(): initialize shift context sctx */
857   ierr = PetscMemzero(&sctx,sizeof(FactorShiftCtx));CHKERRQ(ierr);
858 
859   ierr = PetscMalloc3(am,&rtmp,am,&il,am,&jl);CHKERRQ(ierr);
860 
861   do {
862     sctx.newshift = PETSC_FALSE;
863     for (i=0; i<am; i++) {
864       rtmp[i] = 0.0; jl[i] = am; il[0] = 0;
865     }
866 
867     for (k = 0; k<am; k++) {
868       /* initialize k-th row with elements nonzero in row perm(k) of A */
869       nz   = ai[k+1] - ai[k];
870       acol = aj + ai[k];
871       aval = aa + ai[k];
872       bval = ba + bi[k];
873       while (nz--) {
874         if (*acol < k) { /* skip lower triangular entries */
875           acol++; aval++;
876         } else {
877           rtmp[*acol++] = *aval++;
878           *bval++       = 0.0; /* for in-place factorization */
879         }
880       }
881 
882       /* shift the diagonal of the matrix */
883       if (sctx.nshift) rtmp[k] += sctx.shift_amount;
884 
885       /* modify k-th row by adding in those rows i with U(i,k)!=0 */
886       dk = rtmp[k];
887       i  = jl[k]; /* first row to be added to k_th row  */
888 
889       while (i < k) {
890         nexti = jl[i]; /* next row to be added to k_th row */
891         /* compute multiplier, update D(k) and U(i,k) */
892         ili     = il[i]; /* index of first nonzero element in U(i,k:bms-1) */
893         uikdi   = -ba[ili]*ba[bi[i]];
894         dk     += uikdi*ba[ili];
895         ba[ili] = uikdi; /* -U(i,k) */
896 
897         /* add multiple of row i to k-th row ... */
898         jmin = ili + 1;
899         nz   = bi[i+1] - jmin;
900         if (nz > 0) {
901           bcol = bj + jmin;
902           bval = ba + jmin;
903           while (nz--) rtmp[*bcol++] += uikdi*(*bval++);
904           /* update il and jl for i-th row */
905           il[i] = jmin;
906           j     = bj[jmin]; jl[i] = jl[j]; jl[j] = i;
907         }
908         i = nexti;
909       }
910 
911       /* shift the diagonals when zero pivot is detected */
912       /* compute rs=sum of abs(off-diagonal) */
913       rs   = 0.0;
914       jmin = bi[k]+1;
915       nz   = bi[k+1] - jmin;
916       if (nz) {
917         bcol = bj + jmin;
918         while (nz--) {
919           rs += PetscAbsScalar(rtmp[*bcol]);
920           bcol++;
921         }
922       }
923 
924       sctx.rs = rs;
925       sctx.pv = dk;
926       ierr    = MatPivotCheck(C,A,info,&sctx,k);CHKERRQ(ierr);
927       if (sctx.newshift) break;    /* sctx.shift_amount is updated */
928       dk = sctx.pv;
929 
930       /* copy data into U(k,:) */
931       ba[bi[k]] = 1.0/dk;
932       jmin      = bi[k]+1;
933       nz        = bi[k+1] - jmin;
934       if (nz) {
935         bcol = bj + jmin;
936         bval = ba + jmin;
937         while (nz--) {
938           *bval++       = rtmp[*bcol];
939           rtmp[*bcol++] = 0.0;
940         }
941         /* add k-th row into il and jl */
942         il[k] = jmin;
943         i     = bj[jmin]; jl[k] = jl[i]; jl[i] = k;
944       }
945     }
946   } while (sctx.newshift);
947   ierr = PetscFree3(rtmp,il,jl);CHKERRQ(ierr);
948 
949   C->ops->solve          = MatSolve_SeqSBAIJ_1_NaturalOrdering_inplace;
950   C->ops->solvetranspose = MatSolve_SeqSBAIJ_1_NaturalOrdering_inplace;
951   C->assembled           = PETSC_TRUE;
952   C->preallocated        = PETSC_TRUE;
953 
954   ierr = PetscLogFlops(C->rmap->N);CHKERRQ(ierr);
955   if (sctx.nshift) {
956     if (info->shifttype == (PetscReal)MAT_SHIFT_NONZERO) {
957       ierr = PetscInfo2(A,"number of shiftnz tries %D, shift_amount %g\n",sctx.nshift,(double)sctx.shift_amount);CHKERRQ(ierr);
958     } else if (info->shifttype == (PetscReal)MAT_SHIFT_POSITIVE_DEFINITE) {
959       ierr = PetscInfo2(A,"number of shiftpd tries %D, shift_amount %g\n",sctx.nshift,(double)sctx.shift_amount);CHKERRQ(ierr);
960     }
961   }
962   PetscFunctionReturn(0);
963 }
964 
965 #include <petscbt.h>
966 #include <../src/mat/utils/freespace.h>
967 PetscErrorCode MatICCFactorSymbolic_SeqBAIJ(Mat fact,Mat A,IS perm,const MatFactorInfo *info)
968 {
969   Mat_SeqBAIJ        *a = (Mat_SeqBAIJ*)A->data;
970   Mat_SeqSBAIJ       *b;
971   Mat                B;
972   PetscErrorCode     ierr;
973   PetscBool          perm_identity,missing;
974   PetscInt           reallocs=0,i,*ai=a->i,*aj=a->j,am=a->mbs,bs=A->rmap->bs,*ui;
975   const PetscInt     *rip;
976   PetscInt           jmin,jmax,nzk,k,j,*jl,prow,*il,nextprow;
977   PetscInt           nlnk,*lnk,*lnk_lvl=NULL,ncols,ncols_upper,*cols,*cols_lvl,*uj,**uj_ptr,**uj_lvl_ptr;
978   PetscReal          fill          =info->fill,levels=info->levels;
979   PetscFreeSpaceList free_space    =NULL,current_space=NULL;
980   PetscFreeSpaceList free_space_lvl=NULL,current_space_lvl=NULL;
981   PetscBT            lnkbt;
982 
983   PetscFunctionBegin;
984   ierr = MatMissingDiagonal(A,&missing,&i);CHKERRQ(ierr);
985   if (missing) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Matrix is missing diagonal entry %D",i);
986 
987   if (bs > 1) {
988     if (!a->sbaijMat) {
989       ierr = MatConvert(A,MATSEQSBAIJ,MAT_INITIAL_MATRIX,&a->sbaijMat);CHKERRQ(ierr);
990     }
991     (fact)->ops->iccfactorsymbolic = MatICCFactorSymbolic_SeqSBAIJ;  /* undue the change made in MatGetFactor_seqbaij_petsc */
992 
993     ierr = MatICCFactorSymbolic(fact,a->sbaijMat,perm,info);CHKERRQ(ierr);
994     PetscFunctionReturn(0);
995   }
996 
997   ierr = ISIdentity(perm,&perm_identity);CHKERRQ(ierr);
998   ierr = ISGetIndices(perm,&rip);CHKERRQ(ierr);
999 
1000   /* special case that simply copies fill pattern */
1001   if (!levels && perm_identity) {
1002     ierr = PetscMalloc1(am+1,&ui);CHKERRQ(ierr);
1003     for (i=0; i<am; i++) ui[i] = ai[i+1] - a->diag[i]; /* ui: rowlengths - changes when !perm_identity */
1004     B    = fact;
1005     ierr = MatSeqSBAIJSetPreallocation(B,1,0,ui);CHKERRQ(ierr);
1006 
1007 
1008     b  = (Mat_SeqSBAIJ*)B->data;
1009     uj = b->j;
1010     for (i=0; i<am; i++) {
1011       aj = a->j + a->diag[i];
1012       for (j=0; j<ui[i]; j++) *uj++ = *aj++;
1013       b->ilen[i] = ui[i];
1014     }
1015     ierr = PetscFree(ui);CHKERRQ(ierr);
1016 
1017     B->factortype = MAT_FACTOR_NONE;
1018 
1019     ierr = MatAssemblyBegin(B,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1020     ierr = MatAssemblyEnd(B,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1021     B->factortype = MAT_FACTOR_ICC;
1022 
1023     B->ops->choleskyfactornumeric = MatCholeskyFactorNumeric_SeqBAIJ_N_NaturalOrdering;
1024     PetscFunctionReturn(0);
1025   }
1026 
1027   /* initialization */
1028   ierr  = PetscMalloc1(am+1,&ui);CHKERRQ(ierr);
1029   ui[0] = 0;
1030   ierr  = PetscMalloc1(2*am+1,&cols_lvl);CHKERRQ(ierr);
1031 
1032   /* jl: linked list for storing indices of the pivot rows
1033      il: il[i] points to the 1st nonzero entry of U(i,k:am-1) */
1034   ierr = PetscMalloc4(am,&uj_ptr,am,&uj_lvl_ptr,am,&il,am,&jl);CHKERRQ(ierr);
1035   for (i=0; i<am; i++) {
1036     jl[i] = am; il[i] = 0;
1037   }
1038 
1039   /* create and initialize a linked list for storing column indices of the active row k */
1040   nlnk = am + 1;
1041   ierr = PetscIncompleteLLCreate(am,am,nlnk,lnk,lnk_lvl,lnkbt);CHKERRQ(ierr);
1042 
1043   /* initial FreeSpace size is fill*(ai[am]+am)/2 */
1044   ierr = PetscFreeSpaceGet(PetscRealIntMultTruncate(fill,PetscIntSumTruncate(ai[am]/2,am/2)),&free_space);CHKERRQ(ierr);
1045 
1046   current_space = free_space;
1047 
1048   ierr = PetscFreeSpaceGet(PetscRealIntMultTruncate(fill,PetscIntSumTruncate(ai[am]/2,am/2)),&free_space_lvl);CHKERRQ(ierr);
1049   current_space_lvl = free_space_lvl;
1050 
1051   for (k=0; k<am; k++) {  /* for each active row k */
1052     /* initialize lnk by the column indices of row rip[k] of A */
1053     nzk         = 0;
1054     ncols       = ai[rip[k]+1] - ai[rip[k]];
1055     ncols_upper = 0;
1056     cols        = cols_lvl + am;
1057     for (j=0; j<ncols; j++) {
1058       i = rip[*(aj + ai[rip[k]] + j)];
1059       if (i >= k) { /* only take upper triangular entry */
1060         cols[ncols_upper]     = i;
1061         cols_lvl[ncols_upper] = -1;  /* initialize level for nonzero entries */
1062         ncols_upper++;
1063       }
1064     }
1065     ierr = PetscIncompleteLLAdd(ncols_upper,cols,levels,cols_lvl,am,nlnk,lnk,lnk_lvl,lnkbt);CHKERRQ(ierr);
1066     nzk += nlnk;
1067 
1068     /* update lnk by computing fill-in for each pivot row to be merged in */
1069     prow = jl[k]; /* 1st pivot row */
1070 
1071     while (prow < k) {
1072       nextprow = jl[prow];
1073 
1074       /* merge prow into k-th row */
1075       jmin  = il[prow] + 1; /* index of the 2nd nzero entry in U(prow,k:am-1) */
1076       jmax  = ui[prow+1];
1077       ncols = jmax-jmin;
1078       i     = jmin - ui[prow];
1079       cols  = uj_ptr[prow] + i; /* points to the 2nd nzero entry in U(prow,k:am-1) */
1080       for (j=0; j<ncols; j++) cols_lvl[j] = *(uj_lvl_ptr[prow] + i + j);
1081       ierr = PetscIncompleteLLAddSorted(ncols,cols,levels,cols_lvl,am,nlnk,lnk,lnk_lvl,lnkbt);CHKERRQ(ierr);
1082       nzk += nlnk;
1083 
1084       /* update il and jl for prow */
1085       if (jmin < jmax) {
1086         il[prow] = jmin;
1087 
1088         j = *cols; jl[prow] = jl[j]; jl[j] = prow;
1089       }
1090       prow = nextprow;
1091     }
1092 
1093     /* if free space is not available, make more free space */
1094     if (current_space->local_remaining<nzk) {
1095       i    = am - k + 1; /* num of unfactored rows */
1096       i    = PetscMin(PetscIntMultTruncate(i,nzk), PetscIntMultTruncate(i,i-1)); /* i*nzk, i*(i-1): estimated and max additional space needed */
1097       ierr = PetscFreeSpaceGet(i,&current_space);CHKERRQ(ierr);
1098       ierr = PetscFreeSpaceGet(i,&current_space_lvl);CHKERRQ(ierr);
1099       reallocs++;
1100     }
1101 
1102     /* copy data into free_space and free_space_lvl, then initialize lnk */
1103     ierr = PetscIncompleteLLClean(am,am,nzk,lnk,lnk_lvl,current_space->array,current_space_lvl->array,lnkbt);CHKERRQ(ierr);
1104 
1105     /* add the k-th row into il and jl */
1106     if (nzk-1 > 0) {
1107       i     = current_space->array[1]; /* col value of the first nonzero element in U(k, k+1:am-1) */
1108       jl[k] = jl[i]; jl[i] = k;
1109       il[k] = ui[k] + 1;
1110     }
1111     uj_ptr[k]     = current_space->array;
1112     uj_lvl_ptr[k] = current_space_lvl->array;
1113 
1114     current_space->array           += nzk;
1115     current_space->local_used      += nzk;
1116     current_space->local_remaining -= nzk;
1117 
1118     current_space_lvl->array           += nzk;
1119     current_space_lvl->local_used      += nzk;
1120     current_space_lvl->local_remaining -= nzk;
1121 
1122     ui[k+1] = ui[k] + nzk;
1123   }
1124 
1125   ierr = ISRestoreIndices(perm,&rip);CHKERRQ(ierr);
1126   ierr = PetscFree4(uj_ptr,uj_lvl_ptr,il,jl);CHKERRQ(ierr);
1127   ierr = PetscFree(cols_lvl);CHKERRQ(ierr);
1128 
1129   /* copy free_space into uj and free free_space; set uj in new datastructure; */
1130   ierr = PetscMalloc1(ui[am]+1,&uj);CHKERRQ(ierr);
1131   ierr = PetscFreeSpaceContiguous(&free_space,uj);CHKERRQ(ierr);
1132   ierr = PetscIncompleteLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
1133   ierr = PetscFreeSpaceDestroy(free_space_lvl);CHKERRQ(ierr);
1134 
1135   /* put together the new matrix in MATSEQSBAIJ format */
1136   B    = fact;
1137   ierr = MatSeqSBAIJSetPreallocation(B,1,MAT_SKIP_ALLOCATION,NULL);CHKERRQ(ierr);
1138 
1139   b                = (Mat_SeqSBAIJ*)B->data;
1140   b->singlemalloc  = PETSC_FALSE;
1141   b->free_a        = PETSC_TRUE;
1142   b->free_ij       = PETSC_TRUE;
1143 
1144   ierr = PetscMalloc1(ui[am]+1,&b->a);CHKERRQ(ierr);
1145 
1146   b->j             = uj;
1147   b->i             = ui;
1148   b->diag          = 0;
1149   b->ilen          = 0;
1150   b->imax          = 0;
1151   b->row           = perm;
1152   b->pivotinblocks = PETSC_FALSE; /* need to get from MatFactorInfo */
1153 
1154   ierr    = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr);
1155 
1156   b->icol = perm;
1157 
1158   ierr    = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr);
1159   ierr    = PetscMalloc1(am+1,&b->solve_work);CHKERRQ(ierr);
1160   ierr    = PetscLogObjectMemory((PetscObject)B,(ui[am]-am)*(sizeof(PetscInt)+sizeof(MatScalar)));CHKERRQ(ierr);
1161 
1162   b->maxnz = b->nz = ui[am];
1163 
1164   B->info.factor_mallocs   = reallocs;
1165   B->info.fill_ratio_given = fill;
1166   if (ai[am] != 0.) {
1167     /* nonzeros in lower triangular part of A (includign diagonals)= (ai[am]+am)/2 */
1168     B->info.fill_ratio_needed = ((PetscReal)2*ui[am])/(ai[am]+am);
1169   } else {
1170     B->info.fill_ratio_needed = 0.0;
1171   }
1172 #if defined(PETSC_USE_INFO)
1173   if (ai[am] != 0) {
1174     PetscReal af = B->info.fill_ratio_needed;
1175     ierr = PetscInfo3(A,"Reallocs %D Fill ratio:given %g needed %g\n",reallocs,(double)fill,(double)af);CHKERRQ(ierr);
1176     ierr = PetscInfo1(A,"Run with -pc_factor_fill %g or use \n",(double)af);CHKERRQ(ierr);
1177     ierr = PetscInfo1(A,"PCFactorSetFill(pc,%g) for best performance.\n",(double)af);CHKERRQ(ierr);
1178   } else {
1179     ierr = PetscInfo(A,"Empty matrix.\n");CHKERRQ(ierr);
1180   }
1181 #endif
1182   if (perm_identity) {
1183     B->ops->solve                 = MatSolve_SeqSBAIJ_1_NaturalOrdering_inplace;
1184     B->ops->solvetranspose        = MatSolve_SeqSBAIJ_1_NaturalOrdering_inplace;
1185     B->ops->choleskyfactornumeric = MatCholeskyFactorNumeric_SeqBAIJ_N_NaturalOrdering;
1186   } else {
1187     (fact)->ops->choleskyfactornumeric = MatCholeskyFactorNumeric_SeqBAIJ_N;
1188   }
1189   PetscFunctionReturn(0);
1190 }
1191 
1192 PetscErrorCode MatCholeskyFactorSymbolic_SeqBAIJ(Mat fact,Mat A,IS perm,const MatFactorInfo *info)
1193 {
1194   Mat_SeqBAIJ        *a = (Mat_SeqBAIJ*)A->data;
1195   Mat_SeqSBAIJ       *b;
1196   Mat                B;
1197   PetscErrorCode     ierr;
1198   PetscBool          perm_identity,missing;
1199   PetscReal          fill = info->fill;
1200   const PetscInt     *rip;
1201   PetscInt           i,mbs=a->mbs,bs=A->rmap->bs,*ai=a->i,*aj=a->j,reallocs=0,prow;
1202   PetscInt           *jl,jmin,jmax,nzk,*ui,k,j,*il,nextprow;
1203   PetscInt           nlnk,*lnk,ncols,ncols_upper,*cols,*uj,**ui_ptr,*uj_ptr;
1204   PetscFreeSpaceList free_space=NULL,current_space=NULL;
1205   PetscBT            lnkbt;
1206 
1207   PetscFunctionBegin;
1208   if (bs > 1) { /* convert to seqsbaij */
1209     if (!a->sbaijMat) {
1210       ierr = MatConvert(A,MATSEQSBAIJ,MAT_INITIAL_MATRIX,&a->sbaijMat);CHKERRQ(ierr);
1211     }
1212     (fact)->ops->choleskyfactorsymbolic = MatCholeskyFactorSymbolic_SeqSBAIJ; /* undue the change made in MatGetFactor_seqbaij_petsc */
1213 
1214     ierr = MatCholeskyFactorSymbolic(fact,a->sbaijMat,perm,info);CHKERRQ(ierr);
1215     PetscFunctionReturn(0);
1216   }
1217 
1218   ierr = MatMissingDiagonal(A,&missing,&i);CHKERRQ(ierr);
1219   if (missing) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Matrix is missing diagonal entry %D",i);
1220 
1221   /* check whether perm is the identity mapping */
1222   ierr = ISIdentity(perm,&perm_identity);CHKERRQ(ierr);
1223   if (!perm_identity) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Matrix reordering is not supported");
1224   ierr = ISGetIndices(perm,&rip);CHKERRQ(ierr);
1225 
1226   /* initialization */
1227   ierr  = PetscMalloc1(mbs+1,&ui);CHKERRQ(ierr);
1228   ui[0] = 0;
1229 
1230   /* jl: linked list for storing indices of the pivot rows
1231      il: il[i] points to the 1st nonzero entry of U(i,k:mbs-1) */
1232   ierr = PetscMalloc4(mbs,&ui_ptr,mbs,&il,mbs,&jl,mbs,&cols);CHKERRQ(ierr);
1233   for (i=0; i<mbs; i++) {
1234     jl[i] = mbs; il[i] = 0;
1235   }
1236 
1237   /* create and initialize a linked list for storing column indices of the active row k */
1238   nlnk = mbs + 1;
1239   ierr = PetscLLCreate(mbs,mbs,nlnk,lnk,lnkbt);CHKERRQ(ierr);
1240 
1241   /* initial FreeSpace size is fill* (ai[mbs]+mbs)/2 */
1242   ierr = PetscFreeSpaceGet(PetscRealIntMultTruncate(fill,PetscIntSumTruncate(ai[mbs]/2,mbs/2)),&free_space);CHKERRQ(ierr);
1243 
1244   current_space = free_space;
1245 
1246   for (k=0; k<mbs; k++) {  /* for each active row k */
1247     /* initialize lnk by the column indices of row rip[k] of A */
1248     nzk         = 0;
1249     ncols       = ai[rip[k]+1] - ai[rip[k]];
1250     ncols_upper = 0;
1251     for (j=0; j<ncols; j++) {
1252       i = rip[*(aj + ai[rip[k]] + j)];
1253       if (i >= k) { /* only take upper triangular entry */
1254         cols[ncols_upper] = i;
1255         ncols_upper++;
1256       }
1257     }
1258     ierr = PetscLLAdd(ncols_upper,cols,mbs,nlnk,lnk,lnkbt);CHKERRQ(ierr);
1259     nzk += nlnk;
1260 
1261     /* update lnk by computing fill-in for each pivot row to be merged in */
1262     prow = jl[k]; /* 1st pivot row */
1263 
1264     while (prow < k) {
1265       nextprow = jl[prow];
1266       /* merge prow into k-th row */
1267       jmin   = il[prow] + 1; /* index of the 2nd nzero entry in U(prow,k:mbs-1) */
1268       jmax   = ui[prow+1];
1269       ncols  = jmax-jmin;
1270       uj_ptr = ui_ptr[prow] + jmin - ui[prow]; /* points to the 2nd nzero entry in U(prow,k:mbs-1) */
1271       ierr   = PetscLLAddSorted(ncols,uj_ptr,mbs,nlnk,lnk,lnkbt);CHKERRQ(ierr);
1272       nzk   += nlnk;
1273 
1274       /* update il and jl for prow */
1275       if (jmin < jmax) {
1276         il[prow] = jmin;
1277         j        = *uj_ptr;
1278         jl[prow] = jl[j];
1279         jl[j]    = prow;
1280       }
1281       prow = nextprow;
1282     }
1283 
1284     /* if free space is not available, make more free space */
1285     if (current_space->local_remaining<nzk) {
1286       i    = mbs - k + 1; /* num of unfactored rows */
1287       i    = PetscMin(PetscIntMultTruncate(i,nzk), PetscIntMultTruncate(i,i-1)); /* i*nzk, i*(i-1): estimated and max additional space needed */
1288       ierr = PetscFreeSpaceGet(i,&current_space);CHKERRQ(ierr);
1289       reallocs++;
1290     }
1291 
1292     /* copy data into free space, then initialize lnk */
1293     ierr = PetscLLClean(mbs,mbs,nzk,lnk,current_space->array,lnkbt);CHKERRQ(ierr);
1294 
1295     /* add the k-th row into il and jl */
1296     if (nzk-1 > 0) {
1297       i     = current_space->array[1]; /* col value of the first nonzero element in U(k, k+1:mbs-1) */
1298       jl[k] = jl[i]; jl[i] = k;
1299       il[k] = ui[k] + 1;
1300     }
1301     ui_ptr[k]                       = current_space->array;
1302     current_space->array           += nzk;
1303     current_space->local_used      += nzk;
1304     current_space->local_remaining -= nzk;
1305 
1306     ui[k+1] = ui[k] + nzk;
1307   }
1308 
1309   ierr = ISRestoreIndices(perm,&rip);CHKERRQ(ierr);
1310   ierr = PetscFree4(ui_ptr,il,jl,cols);CHKERRQ(ierr);
1311 
1312   /* copy free_space into uj and free free_space; set uj in new datastructure; */
1313   ierr = PetscMalloc1(ui[mbs]+1,&uj);CHKERRQ(ierr);
1314   ierr = PetscFreeSpaceContiguous(&free_space,uj);CHKERRQ(ierr);
1315   ierr = PetscLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
1316 
1317   /* put together the new matrix in MATSEQSBAIJ format */
1318   B    = fact;
1319   ierr = MatSeqSBAIJSetPreallocation(B,bs,MAT_SKIP_ALLOCATION,NULL);CHKERRQ(ierr);
1320 
1321   b               = (Mat_SeqSBAIJ*)B->data;
1322   b->singlemalloc = PETSC_FALSE;
1323   b->free_a       = PETSC_TRUE;
1324   b->free_ij      = PETSC_TRUE;
1325 
1326   ierr = PetscMalloc1(ui[mbs]+1,&b->a);CHKERRQ(ierr);
1327 
1328   b->j             = uj;
1329   b->i             = ui;
1330   b->diag          = 0;
1331   b->ilen          = 0;
1332   b->imax          = 0;
1333   b->row           = perm;
1334   b->pivotinblocks = PETSC_FALSE; /* need to get from MatFactorInfo */
1335 
1336   ierr     = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr);
1337   b->icol  = perm;
1338   ierr     = PetscObjectReference((PetscObject)perm);CHKERRQ(ierr);
1339   ierr     = PetscMalloc1(mbs+1,&b->solve_work);CHKERRQ(ierr);
1340   ierr     = PetscLogObjectMemory((PetscObject)B,(ui[mbs]-mbs)*(sizeof(PetscInt)+sizeof(MatScalar)));CHKERRQ(ierr);
1341   b->maxnz = b->nz = ui[mbs];
1342 
1343   B->info.factor_mallocs   = reallocs;
1344   B->info.fill_ratio_given = fill;
1345   if (ai[mbs] != 0.) {
1346     /* nonzeros in lower triangular part of A = (ai[mbs]+mbs)/2 */
1347     B->info.fill_ratio_needed = ((PetscReal)2*ui[mbs])/(ai[mbs]+mbs);
1348   } else {
1349     B->info.fill_ratio_needed = 0.0;
1350   }
1351 #if defined(PETSC_USE_INFO)
1352   if (ai[mbs] != 0.) {
1353     PetscReal af = B->info.fill_ratio_needed;
1354     ierr = PetscInfo3(A,"Reallocs %D Fill ratio:given %g needed %g\n",reallocs,(double)fill,(double)af);CHKERRQ(ierr);
1355     ierr = PetscInfo1(A,"Run with -pc_factor_fill %g or use \n",(double)af);CHKERRQ(ierr);
1356     ierr = PetscInfo1(A,"PCFactorSetFill(pc,%g) for best performance.\n",(double)af);CHKERRQ(ierr);
1357   } else {
1358     ierr = PetscInfo(A,"Empty matrix.\n");CHKERRQ(ierr);
1359   }
1360 #endif
1361   if (perm_identity) {
1362     B->ops->choleskyfactornumeric = MatCholeskyFactorNumeric_SeqBAIJ_N_NaturalOrdering;
1363   } else {
1364     B->ops->choleskyfactornumeric = MatCholeskyFactorNumeric_SeqBAIJ_N;
1365   }
1366   PetscFunctionReturn(0);
1367 }
1368 
1369 PetscErrorCode MatSolve_SeqBAIJ_N_NaturalOrdering(Mat A,Vec bb,Vec xx)
1370 {
1371   Mat_SeqBAIJ       *a=(Mat_SeqBAIJ*)A->data;
1372   PetscErrorCode    ierr;
1373   const PetscInt    *ai=a->i,*aj=a->j,*adiag=a->diag,*vi;
1374   PetscInt          i,k,n=a->mbs;
1375   PetscInt          nz,bs=A->rmap->bs,bs2=a->bs2;
1376   const MatScalar   *aa=a->a,*v;
1377   PetscScalar       *x,*s,*t,*ls;
1378   const PetscScalar *b;
1379 
1380   PetscFunctionBegin;
1381   ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr);
1382   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
1383   t    = a->solve_work;
1384 
1385   /* forward solve the lower triangular */
1386   ierr = PetscMemcpy(t,b,bs*sizeof(PetscScalar));CHKERRQ(ierr); /* copy 1st block of b to t */
1387 
1388   for (i=1; i<n; i++) {
1389     v    = aa + bs2*ai[i];
1390     vi   = aj + ai[i];
1391     nz   = ai[i+1] - ai[i];
1392     s    = t + bs*i;
1393     ierr = PetscMemcpy(s,b+bs*i,bs*sizeof(PetscScalar));CHKERRQ(ierr); /* copy i_th block of b to t */
1394     for (k=0;k<nz;k++) {
1395       PetscKernel_v_gets_v_minus_A_times_w(bs,s,v,t+bs*vi[k]);
1396       v += bs2;
1397     }
1398   }
1399 
1400   /* backward solve the upper triangular */
1401   ls = a->solve_work + A->cmap->n;
1402   for (i=n-1; i>=0; i--) {
1403     v    = aa + bs2*(adiag[i+1]+1);
1404     vi   = aj + adiag[i+1]+1;
1405     nz   = adiag[i] - adiag[i+1]-1;
1406     ierr = PetscMemcpy(ls,t+i*bs,bs*sizeof(PetscScalar));CHKERRQ(ierr);
1407     for (k=0; k<nz; k++) {
1408       PetscKernel_v_gets_v_minus_A_times_w(bs,ls,v,t+bs*vi[k]);
1409       v += bs2;
1410     }
1411     PetscKernel_w_gets_A_times_v(bs,ls,aa+bs2*adiag[i],t+i*bs); /* *inv(diagonal[i]) */
1412     ierr = PetscMemcpy(x+i*bs,t+i*bs,bs*sizeof(PetscScalar));CHKERRQ(ierr);
1413   }
1414 
1415   ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr);
1416   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
1417   ierr = PetscLogFlops(2.0*(a->bs2)*(a->nz) - A->rmap->bs*A->cmap->n);CHKERRQ(ierr);
1418   PetscFunctionReturn(0);
1419 }
1420 
1421 PetscErrorCode MatSolve_SeqBAIJ_N(Mat A,Vec bb,Vec xx)
1422 {
1423   Mat_SeqBAIJ        *a   =(Mat_SeqBAIJ*)A->data;
1424   IS                 iscol=a->col,isrow=a->row;
1425   PetscErrorCode     ierr;
1426   const PetscInt     *r,*c,*rout,*cout,*ai=a->i,*aj=a->j,*adiag=a->diag,*vi;
1427   PetscInt           i,m,n=a->mbs;
1428   PetscInt           nz,bs=A->rmap->bs,bs2=a->bs2;
1429   const MatScalar    *aa=a->a,*v;
1430   PetscScalar        *x,*s,*t,*ls;
1431   const PetscScalar  *b;
1432 
1433   PetscFunctionBegin;
1434   ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr);
1435   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
1436   t    = a->solve_work;
1437 
1438   ierr = ISGetIndices(isrow,&rout);CHKERRQ(ierr); r = rout;
1439   ierr = ISGetIndices(iscol,&cout);CHKERRQ(ierr); c = cout;
1440 
1441   /* forward solve the lower triangular */
1442   ierr = PetscMemcpy(t,b+bs*r[0],bs*sizeof(PetscScalar));CHKERRQ(ierr);
1443   for (i=1; i<n; i++) {
1444     v    = aa + bs2*ai[i];
1445     vi   = aj + ai[i];
1446     nz   = ai[i+1] - ai[i];
1447     s    = t + bs*i;
1448     ierr = PetscMemcpy(s,b+bs*r[i],bs*sizeof(PetscScalar));CHKERRQ(ierr);
1449     for (m=0; m<nz; m++) {
1450       PetscKernel_v_gets_v_minus_A_times_w(bs,s,v,t+bs*vi[m]);
1451       v += bs2;
1452     }
1453   }
1454 
1455   /* backward solve the upper triangular */
1456   ls = a->solve_work + A->cmap->n;
1457   for (i=n-1; i>=0; i--) {
1458     v    = aa + bs2*(adiag[i+1]+1);
1459     vi   = aj + adiag[i+1]+1;
1460     nz   = adiag[i] - adiag[i+1] - 1;
1461     ierr = PetscMemcpy(ls,t+i*bs,bs*sizeof(PetscScalar));CHKERRQ(ierr);
1462     for (m=0; m<nz; m++) {
1463       PetscKernel_v_gets_v_minus_A_times_w(bs,ls,v,t+bs*vi[m]);
1464       v += bs2;
1465     }
1466     PetscKernel_w_gets_A_times_v(bs,ls,v,t+i*bs); /* *inv(diagonal[i]) */
1467     ierr = PetscMemcpy(x + bs*c[i],t+i*bs,bs*sizeof(PetscScalar));CHKERRQ(ierr);
1468   }
1469   ierr = ISRestoreIndices(isrow,&rout);CHKERRQ(ierr);
1470   ierr = ISRestoreIndices(iscol,&cout);CHKERRQ(ierr);
1471   ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr);
1472   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
1473   ierr = PetscLogFlops(2.0*(a->bs2)*(a->nz) - A->rmap->bs*A->cmap->n);CHKERRQ(ierr);
1474   PetscFunctionReturn(0);
1475 }
1476 
1477 /*
1478     For each block in an block array saves the largest absolute value in the block into another array
1479 */
1480 static PetscErrorCode MatBlockAbs_private(PetscInt nbs,PetscInt bs2,PetscScalar *blockarray,PetscReal *absarray)
1481 {
1482   PetscErrorCode ierr;
1483   PetscInt       i,j;
1484 
1485   PetscFunctionBegin;
1486   ierr = PetscMemzero(absarray,(nbs+1)*sizeof(PetscReal));CHKERRQ(ierr);
1487   for (i=0; i<nbs; i++) {
1488     for (j=0; j<bs2; j++) {
1489       if (absarray[i] < PetscAbsScalar(blockarray[i*nbs+j])) absarray[i] = PetscAbsScalar(blockarray[i*nbs+j]);
1490     }
1491   }
1492   PetscFunctionReturn(0);
1493 }
1494 
1495 /*
1496      This needs to be renamed and called by the regular MatILUFactor_SeqBAIJ when drop tolerance is used
1497 */
1498 PetscErrorCode MatILUDTFactor_SeqBAIJ(Mat A,IS isrow,IS iscol,const MatFactorInfo *info,Mat *fact)
1499 {
1500   Mat            B = *fact;
1501   Mat_SeqBAIJ    *a=(Mat_SeqBAIJ*)A->data,*b;
1502   IS             isicol;
1503   PetscErrorCode ierr;
1504   const PetscInt *r,*ic;
1505   PetscInt       i,mbs=a->mbs,bs=A->rmap->bs,bs2=a->bs2,*ai=a->i,*aj=a->j,*ajtmp,*adiag;
1506   PetscInt       *bi,*bj,*bdiag;
1507 
1508   PetscInt  row,nzi,nzi_bl,nzi_bu,*im,dtcount,nzi_al,nzi_au;
1509   PetscInt  nlnk,*lnk;
1510   PetscBT   lnkbt;
1511   PetscBool row_identity,icol_identity;
1512   MatScalar *aatmp,*pv,*batmp,*ba,*rtmp,*pc,*multiplier,*vtmp;
1513   PetscInt  j,nz,*pj,*bjtmp,k,ncut,*jtmp;
1514 
1515   PetscReal dt=info->dt;          /* shift=info->shiftamount; */
1516   PetscInt  nnz_max;
1517   PetscBool missing;
1518   PetscReal *vtmp_abs;
1519   MatScalar *v_work;
1520   PetscInt  *v_pivots;
1521   PetscBool allowzeropivot,zeropivotdetected=PETSC_FALSE;
1522 
1523   PetscFunctionBegin;
1524   /* ------- symbolic factorization, can be reused ---------*/
1525   ierr = MatMissingDiagonal(A,&missing,&i);CHKERRQ(ierr);
1526   if (missing) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Matrix is missing diagonal entry %D",i);
1527   adiag=a->diag;
1528 
1529   ierr = ISInvertPermutation(iscol,PETSC_DECIDE,&isicol);CHKERRQ(ierr);
1530 
1531   /* bdiag is location of diagonal in factor */
1532   ierr = PetscMalloc1(mbs+1,&bdiag);CHKERRQ(ierr);
1533 
1534   /* allocate row pointers bi */
1535   ierr = PetscMalloc1(2*mbs+2,&bi);CHKERRQ(ierr);
1536 
1537   /* allocate bj and ba; max num of nonzero entries is (ai[n]+2*n*dtcount+2) */
1538   dtcount = (PetscInt)info->dtcount;
1539   if (dtcount > mbs-1) dtcount = mbs-1;
1540   nnz_max = ai[mbs]+2*mbs*dtcount +2;
1541   /* printf("MatILUDTFactor_SeqBAIJ, bs %d, ai[mbs] %d, nnz_max  %d, dtcount %d\n",bs,ai[mbs],nnz_max,dtcount); */
1542   ierr    = PetscMalloc1(nnz_max,&bj);CHKERRQ(ierr);
1543   nnz_max = nnz_max*bs2;
1544   ierr    = PetscMalloc1(nnz_max,&ba);CHKERRQ(ierr);
1545 
1546   /* put together the new matrix */
1547   ierr = MatSeqBAIJSetPreallocation(B,bs,MAT_SKIP_ALLOCATION,NULL);CHKERRQ(ierr);
1548   ierr = PetscLogObjectParent((PetscObject)B,(PetscObject)isicol);CHKERRQ(ierr);
1549 
1550   b               = (Mat_SeqBAIJ*)(B)->data;
1551   b->free_a       = PETSC_TRUE;
1552   b->free_ij      = PETSC_TRUE;
1553   b->singlemalloc = PETSC_FALSE;
1554 
1555   b->a    = ba;
1556   b->j    = bj;
1557   b->i    = bi;
1558   b->diag = bdiag;
1559   b->ilen = 0;
1560   b->imax = 0;
1561   b->row  = isrow;
1562   b->col  = iscol;
1563 
1564   ierr = PetscObjectReference((PetscObject)isrow);CHKERRQ(ierr);
1565   ierr = PetscObjectReference((PetscObject)iscol);CHKERRQ(ierr);
1566 
1567   b->icol  = isicol;
1568   ierr     = PetscMalloc1(bs*(mbs+1),&b->solve_work);CHKERRQ(ierr);
1569   ierr     = PetscLogObjectMemory((PetscObject)B,nnz_max*(sizeof(PetscInt)+sizeof(MatScalar)));CHKERRQ(ierr);
1570   b->maxnz = nnz_max/bs2;
1571 
1572   (B)->factortype            = MAT_FACTOR_ILUDT;
1573   (B)->info.factor_mallocs   = 0;
1574   (B)->info.fill_ratio_given = ((PetscReal)nnz_max)/((PetscReal)(ai[mbs]*bs2));
1575   /* ------- end of symbolic factorization ---------*/
1576   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
1577   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
1578 
1579   /* linked list for storing column indices of the active row */
1580   nlnk = mbs + 1;
1581   ierr = PetscLLCreate(mbs,mbs,nlnk,lnk,lnkbt);CHKERRQ(ierr);
1582 
1583   /* im: used by PetscLLAddSortedLU(); jtmp: working array for column indices of active row */
1584   ierr = PetscMalloc2(mbs,&im,mbs,&jtmp);CHKERRQ(ierr);
1585   /* rtmp, vtmp: working arrays for sparse and contiguous row entries of active row */
1586   ierr = PetscMalloc2(mbs*bs2,&rtmp,mbs*bs2,&vtmp);CHKERRQ(ierr);
1587   ierr = PetscMalloc1(mbs+1,&vtmp_abs);CHKERRQ(ierr);
1588   ierr = PetscMalloc3(bs,&v_work,bs2,&multiplier,bs,&v_pivots);CHKERRQ(ierr);
1589 
1590   allowzeropivot = PetscNot(A->erroriffailure);
1591   bi[0]       = 0;
1592   bdiag[0]    = (nnz_max/bs2)-1; /* location of diagonal in factor B */
1593   bi[2*mbs+1] = bdiag[0]+1; /* endof bj and ba array */
1594   for (i=0; i<mbs; i++) {
1595     /* copy initial fill into linked list */
1596     nzi = ai[r[i]+1] - ai[r[i]];
1597     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);
1598     nzi_al = adiag[r[i]] - ai[r[i]];
1599     nzi_au = ai[r[i]+1] - adiag[r[i]] -1;
1600 
1601     /* load in initial unfactored row */
1602     ajtmp = aj + ai[r[i]];
1603     ierr  = PetscLLAddPerm(nzi,ajtmp,ic,mbs,nlnk,lnk,lnkbt);CHKERRQ(ierr);
1604     ierr  = PetscMemzero(rtmp,mbs*bs2*sizeof(PetscScalar));CHKERRQ(ierr);
1605     aatmp = a->a + bs2*ai[r[i]];
1606     for (j=0; j<nzi; j++) {
1607       ierr = PetscMemcpy(rtmp+bs2*ic[ajtmp[j]],aatmp+bs2*j,bs2*sizeof(MatScalar));CHKERRQ(ierr);
1608     }
1609 
1610     /* add pivot rows into linked list */
1611     row = lnk[mbs];
1612     while (row < i) {
1613       nzi_bl = bi[row+1] - bi[row] + 1;
1614       bjtmp  = bj + bdiag[row+1]+1; /* points to 1st column next to the diagonal in U */
1615       ierr   = PetscLLAddSortedLU(bjtmp,row,nlnk,lnk,lnkbt,i,nzi_bl,im);CHKERRQ(ierr);
1616       nzi   += nlnk;
1617       row    = lnk[row];
1618     }
1619 
1620     /* copy data from lnk into jtmp, then initialize lnk */
1621     ierr = PetscLLClean(mbs,mbs,nzi,lnk,jtmp,lnkbt);CHKERRQ(ierr);
1622 
1623     /* numerical factorization */
1624     bjtmp = jtmp;
1625     row   = *bjtmp++; /* 1st pivot row */
1626 
1627     while  (row < i) {
1628       pc = rtmp + bs2*row;
1629       pv = ba + bs2*bdiag[row]; /* inv(diag) of the pivot row */
1630       PetscKernel_A_gets_A_times_B(bs,pc,pv,multiplier); /* pc= multiplier = pc*inv(diag[row]) */
1631       ierr = MatBlockAbs_private(1,bs2,pc,vtmp_abs);CHKERRQ(ierr);
1632       if (vtmp_abs[0] > dt) { /* apply tolerance dropping rule */
1633         pj = bj + bdiag[row+1] + 1;         /* point to 1st entry of U(row,:) */
1634         pv = ba + bs2*(bdiag[row+1] + 1);
1635         nz = bdiag[row] - bdiag[row+1] - 1;         /* num of entries in U(row,:), excluding diagonal */
1636         for (j=0; j<nz; j++) {
1637           PetscKernel_A_gets_A_minus_B_times_C(bs,rtmp+bs2*pj[j],pc,pv+bs2*j);
1638         }
1639         /* ierr = PetscLogFlops(bslog*(nz+1.0)-bs);CHKERRQ(ierr); */
1640       }
1641       row = *bjtmp++;
1642     }
1643 
1644     /* copy sparse rtmp into contiguous vtmp; separate L and U part */
1645     nzi_bl = 0; j = 0;
1646     while (jtmp[j] < i) { /* L-part. Note: jtmp is sorted */
1647       ierr = PetscMemcpy(vtmp+bs2*j,rtmp+bs2*jtmp[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
1648       nzi_bl++; j++;
1649     }
1650     nzi_bu = nzi - nzi_bl -1;
1651 
1652     while (j < nzi) { /* U-part */
1653       ierr = PetscMemcpy(vtmp+bs2*j,rtmp+bs2*jtmp[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
1654       j++;
1655     }
1656 
1657     ierr = MatBlockAbs_private(nzi,bs2,vtmp,vtmp_abs);CHKERRQ(ierr);
1658 
1659     bjtmp = bj + bi[i];
1660     batmp = ba + bs2*bi[i];
1661     /* apply level dropping rule to L part */
1662     ncut = nzi_al + dtcount;
1663     if (ncut < nzi_bl) {
1664       ierr = PetscSortSplitReal(ncut,nzi_bl,vtmp_abs,jtmp);CHKERRQ(ierr);
1665       ierr = PetscSortIntWithScalarArray(ncut,jtmp,vtmp);CHKERRQ(ierr);
1666     } else {
1667       ncut = nzi_bl;
1668     }
1669     for (j=0; j<ncut; j++) {
1670       bjtmp[j] = jtmp[j];
1671       ierr     = PetscMemcpy(batmp+bs2*j,rtmp+bs2*bjtmp[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
1672     }
1673     bi[i+1] = bi[i] + ncut;
1674     nzi     = ncut + 1;
1675 
1676     /* apply level dropping rule to U part */
1677     ncut = nzi_au + dtcount;
1678     if (ncut < nzi_bu) {
1679       ierr = PetscSortSplitReal(ncut,nzi_bu,vtmp_abs+nzi_bl+1,jtmp+nzi_bl+1);CHKERRQ(ierr);
1680       ierr = PetscSortIntWithScalarArray(ncut,jtmp+nzi_bl+1,vtmp+nzi_bl+1);CHKERRQ(ierr);
1681     } else {
1682       ncut = nzi_bu;
1683     }
1684     nzi += ncut;
1685 
1686     /* mark bdiagonal */
1687     bdiag[i+1]    = bdiag[i] - (ncut + 1);
1688     bi[2*mbs - i] = bi[2*mbs - i +1] - (ncut + 1);
1689 
1690     bjtmp  = bj + bdiag[i];
1691     batmp  = ba + bs2*bdiag[i];
1692     ierr   = PetscMemcpy(batmp,rtmp+bs2*i,bs2*sizeof(MatScalar));CHKERRQ(ierr);
1693     *bjtmp = i;
1694 
1695     bjtmp = bj + bdiag[i+1]+1;
1696     batmp = ba + (bdiag[i+1]+1)*bs2;
1697 
1698     for (k=0; k<ncut; k++) {
1699       bjtmp[k] = jtmp[nzi_bl+1+k];
1700       ierr     = PetscMemcpy(batmp+bs2*k,rtmp+bs2*bjtmp[k],bs2*sizeof(MatScalar));CHKERRQ(ierr);
1701     }
1702 
1703     im[i] = nzi; /* used by PetscLLAddSortedLU() */
1704 
1705     /* invert diagonal block for simplier triangular solves - add shift??? */
1706     batmp = ba + bs2*bdiag[i];
1707 
1708     ierr  = PetscKernel_A_gets_inverse_A(bs,batmp,v_pivots,v_work,allowzeropivot,&zeropivotdetected);CHKERRQ(ierr);
1709     if (zeropivotdetected) B->factorerrortype = MAT_FACTOR_NUMERIC_ZEROPIVOT;
1710   } /* for (i=0; i<mbs; i++) */
1711   ierr = PetscFree3(v_work,multiplier,v_pivots);CHKERRQ(ierr);
1712 
1713   /* printf("end of L %d, beginning of U %d\n",bi[mbs],bdiag[mbs]); */
1714   if (bi[mbs] >= bdiag[mbs]) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"end of L array %d cannot >= the beginning of U array %d",bi[mbs],bdiag[mbs]);
1715 
1716   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
1717   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
1718 
1719   ierr = PetscLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
1720 
1721   ierr = PetscFree2(im,jtmp);CHKERRQ(ierr);
1722   ierr = PetscFree2(rtmp,vtmp);CHKERRQ(ierr);
1723 
1724   ierr     = PetscLogFlops(bs2*B->cmap->n);CHKERRQ(ierr);
1725   b->maxnz = b->nz = bi[mbs] + bdiag[0] - bdiag[mbs];
1726 
1727   ierr = ISIdentity(isrow,&row_identity);CHKERRQ(ierr);
1728   ierr = ISIdentity(isicol,&icol_identity);CHKERRQ(ierr);
1729   if (row_identity && icol_identity) {
1730     B->ops->solve = MatSolve_SeqBAIJ_N_NaturalOrdering;
1731   } else {
1732     B->ops->solve = MatSolve_SeqBAIJ_N;
1733   }
1734 
1735   B->ops->solveadd          = 0;
1736   B->ops->solvetranspose    = 0;
1737   B->ops->solvetransposeadd = 0;
1738   B->ops->matsolve          = 0;
1739   B->assembled              = PETSC_TRUE;
1740   B->preallocated           = PETSC_TRUE;
1741   PetscFunctionReturn(0);
1742 }
1743