xref: /petsc/src/mat/impls/htool/htool.cxx (revision 7d5fd1e4d9337468ad3f05b65b7facdcd2dfd2a4)
1 #include <../src/mat/impls/htool/htool.hpp> /*I "petscmat.h" I*/
2 #include <petscblaslapack.h>
3 #include <set>
4 
5 #define ALEN(a) (sizeof(a)/sizeof((a)[0]))
6 const char *const MatHtoolCompressorTypes[] = { "sympartialACA", "fullACA", "SVD" };
7 const char *const MatHtoolClusteringTypes[] = { "PCARegular", "PCAGeometric", "BoundingBox1Regular", "BoundingBox1Geometric" };
8 const char HtoolCitation[] = "@article{marchand2020two,\n"
9 "  Author = {Marchand, Pierre and Claeys, Xavier and Jolivet, Pierre and Nataf, Fr\\'ed\\'eric and Tournier, Pierre-Henri},\n"
10 "  Title = {Two-level preconditioning for $h$-version boundary element approximation of hypersingular operator with {GenEO}},\n"
11 "  Year = {2020},\n"
12 "  Publisher = {Elsevier},\n"
13 "  Journal = {Numerische Mathematik},\n"
14 "  Volume = {146},\n"
15 "  Pages = {597--628},\n"
16 "  Url = {https://github.com/htool-ddm/htool}\n"
17 "}\n";
18 static PetscBool HtoolCite = PETSC_FALSE;
19 
20 static PetscErrorCode MatGetDiagonal_Htool(Mat A,Vec v)
21 {
22   Mat_Htool      *a = (Mat_Htool*)A->data;
23   PetscScalar    *x;
24   PetscBool      flg;
25   PetscErrorCode ierr;
26 
27   PetscFunctionBegin;
28   ierr = MatHasCongruentLayouts(A,&flg);CHKERRQ(ierr);
29   if (!flg) SETERRQ(PetscObjectComm((PetscObject)A),PETSC_ERR_SUP,"Only congruent layouts supported");
30   ierr = VecGetArrayWrite(v,&x);CHKERRQ(ierr);
31   a->hmatrix->copy_local_diagonal(x);
32   ierr = VecRestoreArrayWrite(v,&x);CHKERRQ(ierr);
33   ierr = VecScale(v,a->s);CHKERRQ(ierr);
34   PetscFunctionReturn(0);
35 }
36 
37 static PetscErrorCode MatGetDiagonalBlock_Htool(Mat A,Mat *b)
38 {
39   Mat_Htool      *a = (Mat_Htool*)A->data;
40   Mat            B;
41   PetscScalar    *ptr;
42   PetscBool      flg;
43   PetscErrorCode ierr;
44 
45   PetscFunctionBegin;
46   ierr = MatHasCongruentLayouts(A,&flg);CHKERRQ(ierr);
47   if (!flg) SETERRQ(PetscObjectComm((PetscObject)A),PETSC_ERR_SUP,"Only congruent layouts supported");
48   ierr = PetscObjectQuery((PetscObject)A,"DiagonalBlock",(PetscObject*)&B);CHKERRQ(ierr); /* same logic as in MatGetDiagonalBlock_MPIDense() */
49   if (!B) {
50     ierr = MatCreateDense(PETSC_COMM_SELF,A->rmap->n,A->rmap->n,A->rmap->n,A->rmap->n,NULL,&B);CHKERRQ(ierr);
51     ierr = MatDenseGetArrayWrite(B,&ptr);CHKERRQ(ierr);
52     a->hmatrix->copy_local_diagonal_block(ptr);
53     ierr = MatDenseRestoreArrayWrite(B,&ptr);CHKERRQ(ierr);
54     ierr = MatPropagateSymmetryOptions(A,B);CHKERRQ(ierr);
55     ierr = MatAssemblyBegin(B,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
56     ierr = MatAssemblyEnd(B,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
57     ierr = MatScale(B,a->s);CHKERRQ(ierr);
58     ierr = PetscObjectCompose((PetscObject)A,"DiagonalBlock",(PetscObject)B);CHKERRQ(ierr);
59     *b   = B;
60     ierr = MatDestroy(&B);CHKERRQ(ierr);
61   } else *b = B;
62   PetscFunctionReturn(0);
63 }
64 
65 static PetscErrorCode MatMult_Htool(Mat A,Vec x,Vec y)
66 {
67   Mat_Htool         *a = (Mat_Htool*)A->data;
68   const PetscScalar *in;
69   PetscScalar       *out;
70   PetscErrorCode    ierr;
71 
72   PetscFunctionBegin;
73   ierr = VecGetArrayRead(x,&in);CHKERRQ(ierr);
74   ierr = VecGetArrayWrite(y,&out);CHKERRQ(ierr);
75   a->hmatrix->mvprod_local_to_local(in,out);
76   ierr = VecRestoreArrayRead(x,&in);CHKERRQ(ierr);
77   ierr = VecRestoreArrayWrite(y,&out);CHKERRQ(ierr);
78   ierr = VecScale(y,a->s);CHKERRQ(ierr);
79   PetscFunctionReturn(0);
80 }
81 
82 /* naive implementation of MatMultAdd() needed for FEM-BEM coupling via MATNEST */
83 static PetscErrorCode MatMultAdd_Htool(Mat A,Vec v1,Vec v2,Vec v3)
84 {
85   Mat_Htool         *a = (Mat_Htool*)A->data;
86   Vec               tmp;
87   const PetscScalar scale = a->s;
88   PetscErrorCode    ierr;
89 
90   PetscFunctionBegin;
91   ierr = VecDuplicate(v2,&tmp);CHKERRQ(ierr);
92   ierr = VecCopy(v2,v3);CHKERRQ(ierr); /* no-op in MatMultAdd(bA->m[i][j],bx[j],by[i],by[i]) since VecCopy() checks for x == y */
93   a->s = 1.0; /* set s to 1.0 since VecAXPY() may be used to scale the MatMult() output Vec */
94   ierr = MatMult_Htool(A,v1,tmp);CHKERRQ(ierr);
95   ierr = VecAXPY(v3,scale,tmp);CHKERRQ(ierr);
96   ierr = VecDestroy(&tmp);CHKERRQ(ierr);
97   a->s = scale; /* set s back to its original value */
98   PetscFunctionReturn(0);
99 }
100 
101 static PetscErrorCode MatIncreaseOverlap_Htool(Mat A,PetscInt is_max,IS is[],PetscInt ov)
102 {
103   std::set<PetscInt> set;
104   const PetscInt     *idx;
105   PetscInt           *oidx,size;
106   PetscMPIInt        csize;
107   PetscErrorCode     ierr;
108 
109   PetscFunctionBegin;
110   for (PetscInt i=0; i<is_max; ++i) {
111     /* basic implementation that adds indices by shifting an IS by -ov, -ov+1..., -1, 1..., ov-1, ov */
112     /* needed to avoid subdomain matrices to replicate A since it is dense                           */
113     ierr = MPI_Comm_size(PetscObjectComm((PetscObject)is[i]),&csize);CHKERRMPI(ierr);
114     if (csize != 1) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Unsupported parallel IS");
115     ierr = ISGetSize(is[i],&size);CHKERRQ(ierr);
116     ierr = ISGetIndices(is[i],&idx);CHKERRQ(ierr);
117     for (PetscInt j=0; j<size; ++j) {
118       set.insert(idx[j]);
119       for (PetscInt k=1; k<=ov; ++k) {               /* for each layer of overlap      */
120         if (idx[j] - k >= 0) set.insert(idx[j] - k); /* do not insert negative indices */
121         if (idx[j] + k < A->rmap->N && idx[j] + k < A->cmap->N) set.insert(idx[j] + k); /* do not insert indices greater than the dimension of A */
122       }
123     }
124     ierr = ISRestoreIndices(is[i],&idx);CHKERRQ(ierr);
125     ierr = ISDestroy(is+i);CHKERRQ(ierr);
126     size = set.size(); /* size with overlap */
127     ierr = PetscMalloc1(size,&oidx);CHKERRQ(ierr);
128     for (const PetscInt j : set) *oidx++ = j;
129     oidx -= size;
130     ierr = ISCreateGeneral(PETSC_COMM_SELF,size,oidx,PETSC_OWN_POINTER,is+i);CHKERRQ(ierr);
131   }
132   PetscFunctionReturn(0);
133 }
134 
135 static PetscErrorCode MatCreateSubMatrices_Htool(Mat A,PetscInt n,const IS irow[],const IS icol[],MatReuse scall,Mat *submat[])
136 {
137   Mat_Htool         *a = (Mat_Htool*)A->data;
138   Mat               D,B,BT;
139   const PetscScalar *copy;
140   PetscScalar       *ptr;
141   const PetscInt    *idxr,*idxc,*it;
142   PetscInt          nrow,m,i;
143   PetscBool         flg;
144   PetscErrorCode    ierr;
145 
146   PetscFunctionBegin;
147   if (scall != MAT_REUSE_MATRIX) {
148     ierr = PetscCalloc1(n,submat);CHKERRQ(ierr);
149   }
150   for (i=0; i<n; ++i) {
151     ierr = ISGetLocalSize(irow[i],&nrow);CHKERRQ(ierr);
152     ierr = ISGetLocalSize(icol[i],&m);CHKERRQ(ierr);
153     ierr = ISGetIndices(irow[i],&idxr);CHKERRQ(ierr);
154     ierr = ISGetIndices(icol[i],&idxc);CHKERRQ(ierr);
155     if (scall != MAT_REUSE_MATRIX) {
156       ierr = MatCreateDense(PETSC_COMM_SELF,nrow,m,nrow,m,NULL,(*submat)+i);CHKERRQ(ierr);
157     }
158     ierr = MatDenseGetArrayWrite((*submat)[i],&ptr);CHKERRQ(ierr);
159     if (irow[i] == icol[i]) { /* same row and column IS? */
160       ierr = MatHasCongruentLayouts(A,&flg);CHKERRQ(ierr);
161       if (flg) {
162         ierr = ISSorted(irow[i],&flg);CHKERRQ(ierr);
163         if (flg) { /* sorted IS? */
164           it = std::lower_bound(idxr,idxr+nrow,A->rmap->rstart);
165           if (it != idxr+nrow && *it == A->rmap->rstart) { /* rmap->rstart in IS? */
166             if (std::distance(idxr,it) + A->rmap->n <= nrow) { /* long enough IS to store the local diagonal block? */
167               for (PetscInt j=0; j<A->rmap->n && flg; ++j) if (PetscUnlikely(it[j] != A->rmap->rstart+j)) flg = PETSC_FALSE;
168               if (flg) { /* complete local diagonal block in IS? */
169                 /* fast extraction when the local diagonal block is part of the submatrix, e.g., for PCASM or PCHPDDM
170                  *      [   B   C   E   ]
171                  *  A = [   B   D   E   ]
172                  *      [   B   F   E   ]
173                  */
174                 m = std::distance(idxr,it); /* shift of the coefficient (0,0) of block D from above */
175                 ierr = MatGetDiagonalBlock_Htool(A,&D);CHKERRQ(ierr);
176                 ierr = MatDenseGetArrayRead(D,&copy);CHKERRQ(ierr);
177                 for (PetscInt k=0; k<A->rmap->n; ++k) {
178                   ierr = PetscArraycpy(ptr+(m+k)*nrow+m,copy+k*A->rmap->n,A->rmap->n);CHKERRQ(ierr); /* block D from above */
179                 }
180                 ierr = MatDenseRestoreArrayRead(D,&copy);CHKERRQ(ierr);
181                 if (m) {
182                   a->wrapper->copy_submatrix(nrow,m,idxr,idxc,ptr); /* vertical block B from above */
183                   /* entry-wise assembly may be costly, so transpose already-computed entries when possible */
184                   if (A->symmetric || A->hermitian) {
185                     ierr = MatCreateDense(PETSC_COMM_SELF,A->rmap->n,m,A->rmap->n,m,ptr+m,&B);CHKERRQ(ierr);
186                     ierr = MatDenseSetLDA(B,nrow);CHKERRQ(ierr);
187                     ierr = MatCreateDense(PETSC_COMM_SELF,m,A->rmap->n,m,A->rmap->n,ptr+m*nrow,&BT);CHKERRQ(ierr);
188                     ierr = MatDenseSetLDA(BT,nrow);CHKERRQ(ierr);
189                     if (A->hermitian && PetscDefined(USE_COMPLEX)) {
190                       ierr = MatHermitianTranspose(B,MAT_REUSE_MATRIX,&BT);CHKERRQ(ierr);
191                     } else {
192                       ierr = MatTranspose(B,MAT_REUSE_MATRIX,&BT);CHKERRQ(ierr);
193                     }
194                     ierr = MatDestroy(&B);CHKERRQ(ierr);
195                     ierr = MatDestroy(&BT);CHKERRQ(ierr);
196                   } else {
197                     for (PetscInt k=0; k<A->rmap->n; ++k) { /* block C from above */
198                       a->wrapper->copy_submatrix(m,1,idxr,idxc+m+k,ptr+(m+k)*nrow);
199                     }
200                   }
201                 }
202                 if (m+A->rmap->n != nrow) {
203                   a->wrapper->copy_submatrix(nrow,std::distance(it+A->rmap->n,idxr+nrow),idxr,idxc+m+A->rmap->n,ptr+(m+A->rmap->n)*nrow); /* vertical block E from above */
204                   /* entry-wise assembly may be costly, so transpose already-computed entries when possible */
205                   if (A->symmetric || A->hermitian) {
206                     ierr = MatCreateDense(PETSC_COMM_SELF,A->rmap->n,nrow-(m+A->rmap->n),A->rmap->n,nrow-(m+A->rmap->n),ptr+(m+A->rmap->n)*nrow+m,&B);CHKERRQ(ierr);
207                     ierr = MatDenseSetLDA(B,nrow);CHKERRQ(ierr);
208                     ierr = MatCreateDense(PETSC_COMM_SELF,nrow-(m+A->rmap->n),A->rmap->n,nrow-(m+A->rmap->n),A->rmap->n,ptr+m*nrow+m+A->rmap->n,&BT);CHKERRQ(ierr);
209                     ierr = MatDenseSetLDA(BT,nrow);CHKERRQ(ierr);
210                     if (A->hermitian && PetscDefined(USE_COMPLEX)) {
211                       ierr = MatHermitianTranspose(B,MAT_REUSE_MATRIX,&BT);CHKERRQ(ierr);
212                     } else {
213                       ierr = MatTranspose(B,MAT_REUSE_MATRIX,&BT);CHKERRQ(ierr);
214                     }
215                     ierr = MatDestroy(&B);CHKERRQ(ierr);
216                     ierr = MatDestroy(&BT);CHKERRQ(ierr);
217                   } else {
218                     for (PetscInt k=0; k<A->rmap->n; ++k) { /* block F from above */
219                       a->wrapper->copy_submatrix(std::distance(it+A->rmap->n,idxr+nrow),1,it+A->rmap->n,idxc+m+k,ptr+(m+k)*nrow+m+A->rmap->n);
220                     }
221                   }
222                 }
223               } /* complete local diagonal block not in IS */
224             } else flg = PETSC_FALSE; /* IS not long enough to store the local diagonal block */
225           } else flg = PETSC_FALSE; /* rmap->rstart not in IS */
226         } /* unsorted IS */
227       }
228     } else flg = PETSC_FALSE; /* different row and column IS */
229     if (!flg) a->wrapper->copy_submatrix(nrow,m,idxr,idxc,ptr); /* reassemble everything */
230     ierr = ISRestoreIndices(irow[i],&idxr);CHKERRQ(ierr);
231     ierr = ISRestoreIndices(icol[i],&idxc);CHKERRQ(ierr);
232     ierr = MatDenseRestoreArrayWrite((*submat)[i],&ptr);CHKERRQ(ierr);
233     ierr = MatAssemblyBegin((*submat)[i],MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
234     ierr = MatAssemblyEnd((*submat)[i],MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
235     ierr = MatScale((*submat)[i],a->s);CHKERRQ(ierr);
236   }
237   PetscFunctionReturn(0);
238 }
239 
240 static PetscErrorCode MatDestroy_Htool(Mat A)
241 {
242   Mat_Htool               *a = (Mat_Htool*)A->data;
243   PetscContainer          container;
244   MatHtoolKernelTranspose *kernelt;
245   PetscErrorCode          ierr;
246 
247   PetscFunctionBegin;
248   ierr = PetscObjectChangeTypeName((PetscObject)A,NULL);CHKERRQ(ierr);
249   ierr = PetscObjectComposeFunction((PetscObject)A,"MatProductSetFromOptions_htool_seqdense_C",NULL);CHKERRQ(ierr);
250   ierr = PetscObjectComposeFunction((PetscObject)A,"MatProductSetFromOptions_htool_mpidense_C",NULL);CHKERRQ(ierr);
251   ierr = PetscObjectComposeFunction((PetscObject)A,"MatConvert_htool_seqdense_C",NULL);CHKERRQ(ierr);
252   ierr = PetscObjectComposeFunction((PetscObject)A,"MatConvert_htool_mpidense_C",NULL);CHKERRQ(ierr);
253   ierr = PetscObjectComposeFunction((PetscObject)A,"MatHtoolGetHierarchicalMat_C",NULL);CHKERRQ(ierr);
254   ierr = PetscObjectComposeFunction((PetscObject)A,"MatHtoolSetKernel_C",NULL);CHKERRQ(ierr);
255   ierr = PetscObjectComposeFunction((PetscObject)A,"MatHtoolGetPermutationSource_C",NULL);CHKERRQ(ierr);
256   ierr = PetscObjectComposeFunction((PetscObject)A,"MatHtoolGetPermutationTarget_C",NULL);CHKERRQ(ierr);
257   ierr = PetscObjectComposeFunction((PetscObject)A,"MatHtoolUsePermutation_C",NULL);CHKERRQ(ierr);
258   ierr = PetscObjectQuery((PetscObject)A,"KernelTranspose",(PetscObject*)&container);CHKERRQ(ierr);
259   if (container) { /* created in MatTranspose_Htool() */
260     ierr = PetscContainerGetPointer(container,(void**)&kernelt);CHKERRQ(ierr);
261     ierr = MatDestroy(&kernelt->A);CHKERRQ(ierr);
262     ierr = PetscFree(kernelt);CHKERRQ(ierr);
263     ierr = PetscContainerDestroy(&container);CHKERRQ(ierr);
264     ierr = PetscObjectCompose((PetscObject)A,"KernelTranspose",NULL);CHKERRQ(ierr);
265   }
266   if (a->gcoords_source != a->gcoords_target) {
267     ierr = PetscFree(a->gcoords_source);CHKERRQ(ierr);
268   }
269   ierr = PetscFree(a->gcoords_target);CHKERRQ(ierr);
270   ierr = PetscFree2(a->work_source,a->work_target);CHKERRQ(ierr);
271   delete a->wrapper;
272   delete a->hmatrix;
273   ierr = PetscFree(A->data);CHKERRQ(ierr);
274   PetscFunctionReturn(0);
275 }
276 
277 static PetscErrorCode MatView_Htool(Mat A,PetscViewer pv)
278 {
279   Mat_Htool      *a = (Mat_Htool*)A->data;
280   PetscBool      flg;
281   PetscErrorCode ierr;
282 
283   PetscFunctionBegin;
284   ierr = PetscObjectTypeCompare((PetscObject)pv,PETSCVIEWERASCII,&flg);CHKERRQ(ierr);
285   if (flg) {
286     ierr = PetscViewerASCIIPrintf(pv,"symmetry: %c\n",a->hmatrix->get_symmetry_type());CHKERRQ(ierr);
287     if (PetscAbsScalar(a->s-1.0) > PETSC_MACHINE_EPSILON) {
288 #if defined(PETSC_USE_COMPLEX)
289       ierr = PetscViewerASCIIPrintf(pv,"scaling: %g+%gi\n",(double)PetscRealPart(a->s),(double)PetscImaginaryPart(a->s));CHKERRQ(ierr);
290 #else
291       ierr = PetscViewerASCIIPrintf(pv,"scaling: %g\n",(double)a->s);CHKERRQ(ierr);
292 #endif
293     }
294     ierr = PetscViewerASCIIPrintf(pv,"minimum cluster size: %D\n",a->bs[0]);CHKERRQ(ierr);
295     ierr = PetscViewerASCIIPrintf(pv,"maximum block size: %D\n",a->bs[1]);CHKERRQ(ierr);
296     ierr = PetscViewerASCIIPrintf(pv,"epsilon: %g\n",(double)a->epsilon);CHKERRQ(ierr);
297     ierr = PetscViewerASCIIPrintf(pv,"eta: %g\n",(double)a->eta);CHKERRQ(ierr);
298     ierr = PetscViewerASCIIPrintf(pv,"minimum target depth: %D\n",a->depth[0]);CHKERRQ(ierr);
299     ierr = PetscViewerASCIIPrintf(pv,"minimum source depth: %D\n",a->depth[1]);CHKERRQ(ierr);
300     ierr = PetscViewerASCIIPrintf(pv,"compressor: %s\n",MatHtoolCompressorTypes[a->compressor]);CHKERRQ(ierr);
301     ierr = PetscViewerASCIIPrintf(pv,"clustering: %s\n",MatHtoolClusteringTypes[a->clustering]);CHKERRQ(ierr);
302     ierr = PetscViewerASCIIPrintf(pv,"compression ratio: %s\n",a->hmatrix->get_infos("Compression_ratio").c_str());CHKERRQ(ierr);
303     ierr = PetscViewerASCIIPrintf(pv,"space saving: %s\n",a->hmatrix->get_infos("Space_saving").c_str());CHKERRQ(ierr);
304     ierr = PetscViewerASCIIPrintf(pv,"number of dense (resp. low rank) matrices: %s (resp. %s)\n",a->hmatrix->get_infos("Number_of_dmat").c_str(),a->hmatrix->get_infos("Number_of_lrmat").c_str());CHKERRQ(ierr);
305     ierr = PetscViewerASCIIPrintf(pv,"(minimum, mean, maximum) dense block sizes: (%s, %s, %s)\n",a->hmatrix->get_infos("Dense_block_size_min").c_str(),a->hmatrix->get_infos("Dense_block_size_mean").c_str(),a->hmatrix->get_infos("Dense_block_size_max").c_str());CHKERRQ(ierr);
306     ierr = PetscViewerASCIIPrintf(pv,"(minimum, mean, maximum) low rank block sizes: (%s, %s, %s)\n",a->hmatrix->get_infos("Low_rank_block_size_min").c_str(),a->hmatrix->get_infos("Low_rank_block_size_mean").c_str(),a->hmatrix->get_infos("Low_rank_block_size_max").c_str());CHKERRQ(ierr);
307     ierr = PetscViewerASCIIPrintf(pv,"(minimum, mean, maximum) ranks: (%s, %s, %s)\n",a->hmatrix->get_infos("Rank_min").c_str(),a->hmatrix->get_infos("Rank_mean").c_str(),a->hmatrix->get_infos("Rank_max").c_str());CHKERRQ(ierr);
308   }
309   PetscFunctionReturn(0);
310 }
311 
312 static PetscErrorCode MatScale_Htool(Mat A,PetscScalar s)
313 {
314   Mat_Htool *a = (Mat_Htool*)A->data;
315 
316   PetscFunctionBegin;
317   a->s *= s;
318   PetscFunctionReturn(0);
319 }
320 
321 /* naive implementation of MatGetRow() needed for MatConvert_Nest_AIJ() */
322 static PetscErrorCode MatGetRow_Htool(Mat A,PetscInt row,PetscInt *nz,PetscInt **idx,PetscScalar **v)
323 {
324   Mat_Htool      *a = (Mat_Htool*)A->data;
325   PetscInt       *idxc;
326   PetscBLASInt   one = 1,bn;
327   PetscErrorCode ierr;
328 
329   PetscFunctionBegin;
330   if (nz) *nz = A->cmap->N;
331   if (idx || v) { /* even if !idx, need to set idxc for htool::copy_submatrix() */
332     ierr = PetscMalloc1(A->cmap->N,&idxc);CHKERRQ(ierr);
333     for (PetscInt i=0; i<A->cmap->N; ++i) idxc[i] = i;
334   }
335   if (idx) *idx = idxc;
336   if (v) {
337     ierr = PetscMalloc1(A->cmap->N,v);CHKERRQ(ierr);
338     if (a->wrapper) a->wrapper->copy_submatrix(1,A->cmap->N,&row,idxc,*v);
339     else reinterpret_cast<htool::VirtualGenerator<PetscScalar>*>(a->kernelctx)->copy_submatrix(1,A->cmap->N,&row,idxc,*v);
340     ierr = PetscBLASIntCast(A->cmap->N,&bn);CHKERRQ(ierr);
341     PetscStackCallBLAS("BLASscal",BLASscal_(&bn,&a->s,*v,&one));
342   }
343   if (!idx) {
344     ierr = PetscFree(idxc);CHKERRQ(ierr);
345   }
346   PetscFunctionReturn(0);
347 }
348 
349 static PetscErrorCode MatRestoreRow_Htool(Mat A,PetscInt row,PetscInt *nz,PetscInt **idx,PetscScalar **v)
350 {
351   PetscErrorCode ierr;
352 
353   PetscFunctionBegin;
354   if (nz) *nz = 0;
355   if (idx) {
356     ierr = PetscFree(*idx);CHKERRQ(ierr);
357   }
358   if (v) {
359     ierr = PetscFree(*v);CHKERRQ(ierr);
360   }
361   PetscFunctionReturn(0);
362 }
363 
364 static PetscErrorCode MatSetFromOptions_Htool(PetscOptionItems *PetscOptionsObject,Mat A)
365 {
366   Mat_Htool      *a = (Mat_Htool*)A->data;
367   PetscInt       n;
368   PetscBool      flg;
369   PetscErrorCode ierr;
370 
371   PetscFunctionBegin;
372   ierr = PetscOptionsHead(PetscOptionsObject,"Htool options");CHKERRQ(ierr);
373   ierr = PetscOptionsInt("-mat_htool_min_cluster_size","Minimal leaf size in cluster tree",NULL,a->bs[0],a->bs,NULL);CHKERRQ(ierr);
374   ierr = PetscOptionsInt("-mat_htool_max_block_size","Maximal number of coefficients in a dense block",NULL,a->bs[1],a->bs + 1,NULL);CHKERRQ(ierr);
375   ierr = PetscOptionsReal("-mat_htool_epsilon","Relative error in Frobenius norm when approximating a block",NULL,a->epsilon,&a->epsilon,NULL);CHKERRQ(ierr);
376   ierr = PetscOptionsReal("-mat_htool_eta","Admissibility condition tolerance",NULL,a->eta,&a->eta,NULL);CHKERRQ(ierr);
377   ierr = PetscOptionsInt("-mat_htool_min_target_depth","Minimal cluster tree depth associated with the rows",NULL,a->depth[0],a->depth,NULL);CHKERRQ(ierr);
378   ierr = PetscOptionsInt("-mat_htool_min_source_depth","Minimal cluster tree depth associated with the columns",NULL,a->depth[1],a->depth + 1,NULL);CHKERRQ(ierr);
379   n = 0;
380   ierr = PetscOptionsEList("-mat_htool_compressor","Type of compression","MatHtoolCompressorType",MatHtoolCompressorTypes,ALEN(MatHtoolCompressorTypes),MatHtoolCompressorTypes[MAT_HTOOL_COMPRESSOR_SYMPARTIAL_ACA],&n,&flg);CHKERRQ(ierr);
381   if (flg) a->compressor = MatHtoolCompressorType(n);
382   n = 0;
383   ierr = PetscOptionsEList("-mat_htool_clustering","Type of clustering","MatHtoolClusteringType",MatHtoolClusteringTypes,ALEN(MatHtoolClusteringTypes),MatHtoolClusteringTypes[MAT_HTOOL_CLUSTERING_PCA_REGULAR],&n,&flg);CHKERRQ(ierr);
384   if (flg) a->clustering = MatHtoolClusteringType(n);
385   ierr = PetscOptionsTail();CHKERRQ(ierr);
386   PetscFunctionReturn(0);
387 }
388 
389 static PetscErrorCode MatAssemblyEnd_Htool(Mat A,MatAssemblyType type)
390 {
391   Mat_Htool                                                    *a = (Mat_Htool*)A->data;
392   const PetscInt                                               *ranges;
393   PetscInt                                                     *offset;
394   PetscMPIInt                                                  size;
395   char                                                         S = PetscDefined(USE_COMPLEX) && A->hermitian ? 'H' : (A->symmetric ? 'S' : 'N'),uplo = S == 'N' ? 'N' : 'U';
396   htool::VirtualGenerator<PetscScalar>                         *generator = nullptr;
397   std::shared_ptr<htool::VirtualCluster>                       t,s = nullptr;
398   std::shared_ptr<htool::VirtualLowRankGenerator<PetscScalar>> compressor = nullptr;
399   PetscErrorCode                                               ierr;
400 
401   PetscFunctionBegin;
402   ierr = PetscCitationsRegister(HtoolCitation,&HtoolCite);CHKERRQ(ierr);
403   delete a->wrapper;
404   delete a->hmatrix;
405   ierr = MPI_Comm_size(PetscObjectComm((PetscObject)A),&size);CHKERRMPI(ierr);
406   ierr = PetscMalloc1(2*size,&offset);CHKERRQ(ierr);
407   ierr = MatGetOwnershipRanges(A,&ranges);CHKERRQ(ierr);
408   for (PetscInt i=0; i<size; ++i) {
409     offset[2*i] = ranges[i];
410     offset[2*i+1] = ranges[i+1] - ranges[i];
411   }
412   switch (a->clustering) {
413   case MAT_HTOOL_CLUSTERING_PCA_GEOMETRIC:
414     t = std::make_shared<htool::Cluster<htool::PCA<htool::SplittingTypes::GeometricSplitting>>>(a->dim);
415     break;
416   case MAT_HTOOL_CLUSTERING_BOUNDING_BOX_1_GEOMETRIC:
417     t = std::make_shared<htool::Cluster<htool::BoundingBox1<htool::SplittingTypes::GeometricSplitting>>>(a->dim);
418     break;
419   case MAT_HTOOL_CLUSTERING_BOUNDING_BOX_1_REGULAR:
420     t = std::make_shared<htool::Cluster<htool::BoundingBox1<htool::SplittingTypes::RegularSplitting>>>(a->dim);
421     break;
422   default:
423     t = std::make_shared<htool::Cluster<htool::PCA<htool::SplittingTypes::RegularSplitting>>>(a->dim);
424   }
425   t->set_minclustersize(a->bs[0]);
426   t->build(A->rmap->N,a->gcoords_target,offset);
427   if (a->kernel) a->wrapper = new WrapperHtool(A->rmap->N,A->cmap->N,a->dim,a->kernel,a->kernelctx);
428   else {
429     a->wrapper = NULL;
430     generator = reinterpret_cast<htool::VirtualGenerator<PetscScalar>*>(a->kernelctx);
431   }
432   if (a->gcoords_target != a->gcoords_source) {
433     ierr = MatGetOwnershipRangesColumn(A,&ranges);CHKERRQ(ierr);
434     for (PetscInt i=0; i<size; ++i) {
435       offset[2*i] = ranges[i];
436       offset[2*i+1] = ranges[i+1] - ranges[i];
437     }
438     switch (a->clustering) {
439     case MAT_HTOOL_CLUSTERING_PCA_GEOMETRIC:
440       s = std::make_shared<htool::Cluster<htool::PCA<htool::SplittingTypes::GeometricSplitting>>>(a->dim);
441       break;
442     case MAT_HTOOL_CLUSTERING_BOUNDING_BOX_1_GEOMETRIC:
443       s = std::make_shared<htool::Cluster<htool::BoundingBox1<htool::SplittingTypes::GeometricSplitting>>>(a->dim);
444       break;
445     case MAT_HTOOL_CLUSTERING_BOUNDING_BOX_1_REGULAR:
446       s = std::make_shared<htool::Cluster<htool::BoundingBox1<htool::SplittingTypes::RegularSplitting>>>(a->dim);
447       break;
448     default:
449       s = std::make_shared<htool::Cluster<htool::PCA<htool::SplittingTypes::RegularSplitting>>>(a->dim);
450     }
451     s->set_minclustersize(a->bs[0]);
452     s->build(A->cmap->N,a->gcoords_source,offset);
453     S = uplo = 'N';
454   }
455   ierr = PetscFree(offset);CHKERRQ(ierr);
456   switch (a->compressor) {
457   case MAT_HTOOL_COMPRESSOR_FULL_ACA:
458     compressor = std::make_shared<htool::fullACA<PetscScalar>>();
459     break;
460   case MAT_HTOOL_COMPRESSOR_SVD:
461     compressor = std::make_shared<htool::SVD<PetscScalar>>();
462     break;
463   default:
464     compressor = std::make_shared<htool::sympartialACA<PetscScalar>>();
465   }
466   a->hmatrix = dynamic_cast<htool::VirtualHMatrix<PetscScalar>*>(new htool::HMatrix<PetscScalar>(t,s ? s : t,a->epsilon,a->eta,S,uplo));
467   a->hmatrix->set_compression(compressor);
468   a->hmatrix->set_maxblocksize(a->bs[1]);
469   a->hmatrix->set_mintargetdepth(a->depth[0]);
470   a->hmatrix->set_minsourcedepth(a->depth[1]);
471   if (s) a->hmatrix->build(a->wrapper ? *a->wrapper : *generator,a->gcoords_target,a->gcoords_source);
472   else   a->hmatrix->build(a->wrapper ? *a->wrapper : *generator,a->gcoords_target);
473   PetscFunctionReturn(0);
474 }
475 
476 static PetscErrorCode MatProductNumeric_Htool(Mat C)
477 {
478   Mat_Product       *product = C->product;
479   Mat_Htool         *a = (Mat_Htool*)product->A->data;
480   const PetscScalar *in;
481   PetscScalar       *out;
482   PetscInt          lda;
483   PetscErrorCode    ierr;
484 
485   PetscFunctionBegin;
486   MatCheckProduct(C,1);
487   switch (product->type) {
488   case MATPRODUCT_AB:
489     PetscInt N;
490     ierr = MatGetSize(C,NULL,&N);CHKERRQ(ierr);
491     ierr = MatDenseGetLDA(C,&lda);CHKERRQ(ierr);
492     if (lda != C->rmap->n) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_SUP,"Unsupported leading dimension (%D != %D)",lda,C->rmap->n);
493     ierr = MatDenseGetArrayRead(product->B,&in);CHKERRQ(ierr);
494     ierr = MatDenseGetArrayWrite(C,&out);CHKERRQ(ierr);
495     a->hmatrix->mvprod_local_to_local(in,out,N);
496     ierr = MatDenseRestoreArrayWrite(C,&out);CHKERRQ(ierr);
497     ierr = MatDenseRestoreArrayRead(product->B,&in);CHKERRQ(ierr);
498     ierr = MatScale(C,a->s);CHKERRQ(ierr);
499     break;
500   default:
501     SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_SUP,"MatProductType %s is not supported",MatProductTypes[product->type]);
502   }
503   PetscFunctionReturn(0);
504 }
505 
506 static PetscErrorCode MatProductSymbolic_Htool(Mat C)
507 {
508   Mat_Product    *product = C->product;
509   Mat            A,B;
510   PetscBool      flg;
511   PetscErrorCode ierr;
512 
513   PetscFunctionBegin;
514   MatCheckProduct(C,1);
515   A = product->A;
516   B = product->B;
517   ierr = PetscObjectTypeCompareAny((PetscObject)B,&flg,MATSEQDENSE,MATMPIDENSE,"");CHKERRQ(ierr);
518   if (!flg) SETERRQ1(PetscObjectComm((PetscObject)B),PETSC_ERR_SUP,"MatProduct_AB not supported for %s",((PetscObject)product->B)->type_name);
519   switch (product->type) {
520   case MATPRODUCT_AB:
521     if (C->rmap->n == PETSC_DECIDE || C->cmap->n == PETSC_DECIDE || C->rmap->N == PETSC_DECIDE || C->cmap->N == PETSC_DECIDE) {
522       ierr = MatSetSizes(C,A->rmap->n,B->cmap->n,A->rmap->N,B->cmap->N);CHKERRQ(ierr);
523     }
524     ierr = MatSetType(C,MATDENSE);CHKERRQ(ierr);
525     ierr = MatSetUp(C);CHKERRQ(ierr);
526     ierr = MatSetOption(C,MAT_NO_OFF_PROC_ENTRIES,PETSC_TRUE);CHKERRQ(ierr);
527     ierr = MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
528     ierr = MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
529     break;
530   default:
531     SETERRQ1(PetscObjectComm((PetscObject)B),PETSC_ERR_SUP,"ProductType %s is not supported",MatProductTypes[product->type]);
532   }
533   C->ops->productsymbolic = NULL;
534   C->ops->productnumeric = MatProductNumeric_Htool;
535   PetscFunctionReturn(0);
536 }
537 
538 static PetscErrorCode MatProductSetFromOptions_Htool(Mat C)
539 {
540   PetscFunctionBegin;
541   MatCheckProduct(C,1);
542   if (C->product->type == MATPRODUCT_AB) C->ops->productsymbolic = MatProductSymbolic_Htool;
543   PetscFunctionReturn(0);
544 }
545 
546 static PetscErrorCode MatHtoolGetHierarchicalMat_Htool(Mat A,const htool::VirtualHMatrix<PetscScalar> **hmatrix)
547 {
548   Mat_Htool *a = (Mat_Htool*)A->data;
549 
550   PetscFunctionBegin;
551   *hmatrix = a->hmatrix;
552   PetscFunctionReturn(0);
553 }
554 
555 /*@C
556      MatHtoolGetHierarchicalMat - Retrieves the opaque pointer to a Htool virtual matrix stored in a MATHTOOL.
557 
558    Input Parameter:
559 .     A - hierarchical matrix
560 
561    Output Parameter:
562 .     hmatrix - opaque pointer to a Htool virtual matrix
563 
564    Level: advanced
565 
566 .seealso:  MATHTOOL
567 @*/
568 PETSC_EXTERN PetscErrorCode MatHtoolGetHierarchicalMat(Mat A,const htool::VirtualHMatrix<PetscScalar> **hmatrix)
569 {
570   PetscErrorCode ierr;
571 
572   PetscFunctionBegin;
573   PetscValidHeaderSpecific(A,MAT_CLASSID,1);
574   PetscValidPointer(hmatrix,2);
575   ierr = PetscTryMethod(A,"MatHtoolGetHierarchicalMat_C",(Mat,const htool::VirtualHMatrix<PetscScalar>**),(A,hmatrix));CHKERRQ(ierr);
576   PetscFunctionReturn(0);
577 }
578 
579 static PetscErrorCode MatHtoolSetKernel_Htool(Mat A,MatHtoolKernel kernel,void *kernelctx)
580 {
581   Mat_Htool *a = (Mat_Htool*)A->data;
582 
583   PetscFunctionBegin;
584   a->kernel    = kernel;
585   a->kernelctx = kernelctx;
586   delete a->wrapper;
587   if (a->kernel) a->wrapper = new WrapperHtool(A->rmap->N,A->cmap->N,a->dim,a->kernel,a->kernelctx);
588   PetscFunctionReturn(0);
589 }
590 
591 /*@C
592      MatHtoolSetKernel - Sets the kernel and context used for the assembly of a MATHTOOL.
593 
594    Input Parameters:
595 +     A - hierarchical matrix
596 .     kernel - computational kernel (or NULL)
597 -     kernelctx - kernel context (if kernel is NULL, the pointer must be of type htool::VirtualGenerator<PetscScalar>*)
598 
599    Level: advanced
600 
601 .seealso:  MATHTOOL, MatCreateHtoolFromKernel()
602 @*/
603 PETSC_EXTERN PetscErrorCode MatHtoolSetKernel(Mat A,MatHtoolKernel kernel,void *kernelctx)
604 {
605   PetscErrorCode ierr;
606 
607   PetscFunctionBegin;
608   PetscValidHeaderSpecific(A,MAT_CLASSID,1);
609   if (!kernelctx) PetscValidFunction(kernel,2);
610   if (!kernel)    PetscValidPointer(kernelctx,3);
611   ierr = PetscTryMethod(A,"MatHtoolSetKernel_C",(Mat,MatHtoolKernel,void*),(A,kernel,kernelctx));CHKERRQ(ierr);
612   PetscFunctionReturn(0);
613 }
614 
615 static PetscErrorCode MatHtoolGetPermutationSource_Htool(Mat A,IS* is)
616 {
617   Mat_Htool             *a = (Mat_Htool*)A->data;
618   std::vector<PetscInt> source;
619   PetscErrorCode        ierr;
620 
621   PetscFunctionBegin;
622   source = a->hmatrix->get_local_perm_source();
623   ierr = ISCreateGeneral(PetscObjectComm((PetscObject)A),source.size(),source.data(),PETSC_COPY_VALUES,is);CHKERRQ(ierr);
624   ierr = ISSetPermutation(*is);CHKERRQ(ierr);
625   PetscFunctionReturn(0);
626 }
627 
628 /*@C
629      MatHtoolGetPermutationSource - Gets the permutation associated to the source cluster.
630 
631    Input Parameter:
632 .     A - hierarchical matrix
633 
634    Output Parameter:
635 .     is - permutation
636 
637    Level: advanced
638 
639 .seealso:  MATHTOOL, MatHtoolGetPermutationTarget(), MatHtoolUsePermutation()
640 @*/
641 PETSC_EXTERN PetscErrorCode MatHtoolGetPermutationSource(Mat A,IS* is)
642 {
643   PetscErrorCode ierr;
644 
645   PetscFunctionBegin;
646   PetscValidHeaderSpecific(A,MAT_CLASSID,1);
647   if (!is) PetscValidPointer(is,2);
648   ierr = PetscTryMethod(A,"MatHtoolGetPermutationSource_C",(Mat,IS*),(A,is));CHKERRQ(ierr);
649   PetscFunctionReturn(0);
650 }
651 
652 static PetscErrorCode MatHtoolGetPermutationTarget_Htool(Mat A,IS* is)
653 {
654   Mat_Htool             *a = (Mat_Htool*)A->data;
655   std::vector<PetscInt> target;
656   PetscErrorCode        ierr;
657 
658   PetscFunctionBegin;
659   target = a->hmatrix->get_local_perm_target();
660   ierr = ISCreateGeneral(PetscObjectComm((PetscObject)A),target.size(),target.data(),PETSC_COPY_VALUES,is);CHKERRQ(ierr);
661   ierr = ISSetPermutation(*is);CHKERRQ(ierr);
662   PetscFunctionReturn(0);
663 }
664 
665 /*@C
666      MatHtoolGetPermutationTarget - Gets the permutation associated to the target cluster.
667 
668    Input Parameter:
669 .     A - hierarchical matrix
670 
671    Output Parameter:
672 .     is - permutation
673 
674    Level: advanced
675 
676 .seealso:  MATHTOOL, MatHtoolGetPermutationSource(), MatHtoolUsePermutation()
677 @*/
678 PETSC_EXTERN PetscErrorCode MatHtoolGetPermutationTarget(Mat A,IS* is)
679 {
680   PetscErrorCode ierr;
681 
682   PetscFunctionBegin;
683   PetscValidHeaderSpecific(A,MAT_CLASSID,1);
684   if (!is) PetscValidPointer(is,2);
685   ierr = PetscTryMethod(A,"MatHtoolGetPermutationTarget_C",(Mat,IS*),(A,is));CHKERRQ(ierr);
686   PetscFunctionReturn(0);
687 }
688 
689 static PetscErrorCode MatHtoolUsePermutation_Htool(Mat A,PetscBool use)
690 {
691   Mat_Htool *a = (Mat_Htool*)A->data;
692 
693   PetscFunctionBegin;
694   a->hmatrix->set_use_permutation(use);
695   PetscFunctionReturn(0);
696 }
697 
698 /*@C
699      MatHtoolUsePermutation - Sets whether MATHTOOL should permute input (resp. output) vectors following its internal source (resp. target) permutation.
700 
701    Input Parameters:
702 +     A - hierarchical matrix
703 -     use - Boolean value
704 
705    Level: advanced
706 
707 .seealso:  MATHTOOL, MatHtoolGetPermutationSource(), MatHtoolGetPermutationTarget()
708 @*/
709 PETSC_EXTERN PetscErrorCode MatHtoolUsePermutation(Mat A,PetscBool use)
710 {
711   PetscErrorCode ierr;
712 
713   PetscFunctionBegin;
714   PetscValidHeaderSpecific(A,MAT_CLASSID,1);
715   PetscValidLogicalCollectiveBool(A,use,2);
716   ierr = PetscTryMethod(A,"MatHtoolUsePermutation_C",(Mat,PetscBool),(A,use));CHKERRQ(ierr);
717   PetscFunctionReturn(0);
718 }
719 
720 static PetscErrorCode MatConvert_Htool_Dense(Mat A,MatType newtype,MatReuse reuse,Mat *B)
721 {
722   Mat            C;
723   Mat_Htool      *a = (Mat_Htool*)A->data;
724   PetscInt       lda;
725   PetscScalar    *array;
726   PetscErrorCode ierr;
727 
728   PetscFunctionBegin;
729   if (reuse == MAT_REUSE_MATRIX) {
730     C = *B;
731     if (C->rmap->n != A->rmap->n || C->cmap->N != A->cmap->N) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Incompatible dimensions");
732     ierr = MatDenseGetLDA(C,&lda);CHKERRQ(ierr);
733     if (lda != C->rmap->n) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_SUP,"Unsupported leading dimension (%D != %D)",lda,C->rmap->n);
734   } else {
735     ierr = MatCreate(PetscObjectComm((PetscObject)A),&C);CHKERRQ(ierr);
736     ierr = MatSetSizes(C,A->rmap->n,A->cmap->n,A->rmap->N,A->cmap->N);CHKERRQ(ierr);
737     ierr = MatSetType(C,MATDENSE);CHKERRQ(ierr);
738     ierr = MatSetUp(C);CHKERRQ(ierr);
739     ierr = MatSetOption(C,MAT_NO_OFF_PROC_ENTRIES,PETSC_TRUE);CHKERRQ(ierr);
740   }
741   ierr = MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
742   ierr = MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
743   ierr = MatDenseGetArrayWrite(C,&array);CHKERRQ(ierr);
744   a->hmatrix->copy_local_dense_perm(array);
745   ierr = MatDenseRestoreArrayWrite(C,&array);CHKERRQ(ierr);
746   ierr = MatScale(C,a->s);CHKERRQ(ierr);
747   if (reuse == MAT_INPLACE_MATRIX) {
748     ierr = MatHeaderReplace(A,&C);CHKERRQ(ierr);
749   } else *B = C;
750   PetscFunctionReturn(0);
751 }
752 
753 static PetscErrorCode GenEntriesTranspose(PetscInt sdim,PetscInt M,PetscInt N,const PetscInt *rows,const PetscInt *cols,PetscScalar *ptr,void *ctx)
754 {
755   MatHtoolKernelTranspose *generator = (MatHtoolKernelTranspose*)ctx;
756   PetscScalar             *tmp;
757   PetscErrorCode          ierr;
758 
759   PetscFunctionBegin;
760   generator->kernel(sdim,N,M,cols,rows,ptr,generator->kernelctx);
761   ierr = PetscMalloc1(M*N,&tmp);CHKERRQ(ierr);
762   ierr = PetscArraycpy(tmp,ptr,M*N);CHKERRQ(ierr);
763   for (PetscInt i=0; i<M; ++i) {
764     for (PetscInt j=0; j<N; ++j) ptr[i+j*M] = tmp[j+i*N];
765   }
766   ierr = PetscFree(tmp);CHKERRQ(ierr);
767   PetscFunctionReturn(0);
768 }
769 
770 /* naive implementation which keeps a reference to the original Mat */
771 static PetscErrorCode MatTranspose_Htool(Mat A,MatReuse reuse,Mat *B)
772 {
773   Mat                     C;
774   Mat_Htool               *a = (Mat_Htool*)A->data,*c;
775   PetscInt                M = A->rmap->N,N = A->cmap->N,m = A->rmap->n,n = A->cmap->n;
776   PetscContainer          container;
777   MatHtoolKernelTranspose *kernelt;
778   PetscErrorCode          ierr;
779 
780   PetscFunctionBegin;
781   if (reuse == MAT_INPLACE_MATRIX) SETERRQ(PetscObjectComm((PetscObject)A),PETSC_ERR_SUP,"MatTranspose() with MAT_INPLACE_MATRIX not supported");
782   if (reuse == MAT_INITIAL_MATRIX) {
783     ierr = MatCreate(PetscObjectComm((PetscObject)A),&C);CHKERRQ(ierr);
784     ierr = MatSetSizes(C,n,m,N,M);CHKERRQ(ierr);
785     ierr = MatSetType(C,((PetscObject)A)->type_name);CHKERRQ(ierr);
786     ierr = MatSetUp(C);CHKERRQ(ierr);
787     ierr = PetscContainerCreate(PetscObjectComm((PetscObject)C),&container);CHKERRQ(ierr);
788     ierr = PetscNew(&kernelt);CHKERRQ(ierr);
789     ierr = PetscContainerSetPointer(container,kernelt);CHKERRQ(ierr);
790     ierr = PetscObjectCompose((PetscObject)C,"KernelTranspose",(PetscObject)container);CHKERRQ(ierr);
791   } else {
792     C = *B;
793     ierr = PetscObjectQuery((PetscObject)C,"KernelTranspose",(PetscObject*)&container);CHKERRQ(ierr);
794     if (!container) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"Must call MatTranspose() with MAT_INITIAL_MATRIX first");
795     ierr = PetscContainerGetPointer(container,(void**)&kernelt);CHKERRQ(ierr);
796   }
797   c                  = (Mat_Htool*)C->data;
798   c->dim             = a->dim;
799   c->s               = a->s;
800   c->kernel          = GenEntriesTranspose;
801   if (kernelt->A != A) {
802     ierr = MatDestroy(&kernelt->A);CHKERRQ(ierr);
803     kernelt->A       = A;
804     ierr = PetscObjectReference((PetscObject)A);CHKERRQ(ierr);
805   }
806   kernelt->kernel    = a->kernel;
807   kernelt->kernelctx = a->kernelctx;
808   c->kernelctx       = kernelt;
809   if (reuse == MAT_INITIAL_MATRIX) {
810     ierr = PetscMalloc1(N*c->dim,&c->gcoords_target);CHKERRQ(ierr);
811     ierr = PetscArraycpy(c->gcoords_target,a->gcoords_source,N*c->dim);CHKERRQ(ierr);
812     if (a->gcoords_target != a->gcoords_source) {
813       ierr = PetscMalloc1(M*c->dim,&c->gcoords_source);CHKERRQ(ierr);
814       ierr = PetscArraycpy(c->gcoords_source,a->gcoords_target,M*c->dim);CHKERRQ(ierr);
815     } else c->gcoords_source = c->gcoords_target;
816     ierr = PetscCalloc2(M,&c->work_source,N,&c->work_target);CHKERRQ(ierr);
817   }
818   ierr = MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
819   ierr = MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
820   if (reuse == MAT_INITIAL_MATRIX) *B = C;
821   PetscFunctionReturn(0);
822 }
823 
824 /*@C
825      MatCreateHtoolFromKernel - Creates a MATHTOOL from a user-supplied kernel.
826 
827    Input Parameters:
828 +     comm - MPI communicator
829 .     m - number of local rows (or PETSC_DECIDE to have calculated if M is given)
830 .     n - number of local columns (or PETSC_DECIDE to have calculated if N is given)
831 .     M - number of global rows (or PETSC_DETERMINE to have calculated if m is given)
832 .     N - number of global columns (or PETSC_DETERMINE to have calculated if n is given)
833 .     spacedim - dimension of the space coordinates
834 .     coords_target - coordinates of the target
835 .     coords_source - coordinates of the source
836 .     kernel - computational kernel (or NULL)
837 -     kernelctx - kernel context (if kernel is NULL, the pointer must be of type htool::VirtualGenerator<PetscScalar>*)
838 
839    Output Parameter:
840 .     B - matrix
841 
842    Options Database Keys:
843 +     -mat_htool_min_cluster_size <PetscInt> - minimal leaf size in cluster tree
844 .     -mat_htool_max_block_size <PetscInt> - maximal number of coefficients in a dense block
845 .     -mat_htool_epsilon <PetscReal> - relative error in Frobenius norm when approximating a block
846 .     -mat_htool_eta <PetscReal> - admissibility condition tolerance
847 .     -mat_htool_min_target_depth <PetscInt> - minimal cluster tree depth associated with the rows
848 .     -mat_htool_min_source_depth <PetscInt> - minimal cluster tree depth associated with the columns
849 .     -mat_htool_compressor <sympartialACA, fullACA, SVD> - type of compression
850 -     -mat_htool_clustering <PCARegular, PCAGeometric, BounbingBox1Regular, BoundingBox1Geometric> - type of clustering
851 
852    Level: intermediate
853 
854 .seealso:  MatCreate(), MATHTOOL, PCSetCoordinates(), MatHtoolSetKernel(), MatHtoolCompressorType, MATH2OPUS, MatCreateH2OpusFromKernel()
855 @*/
856 PetscErrorCode MatCreateHtoolFromKernel(MPI_Comm comm,PetscInt m,PetscInt n,PetscInt M,PetscInt N,PetscInt spacedim,const PetscReal coords_target[],const PetscReal coords_source[],MatHtoolKernel kernel,void *kernelctx,Mat *B)
857 {
858   Mat            A;
859   Mat_Htool      *a;
860   PetscErrorCode ierr;
861 
862   PetscFunctionBegin;
863   ierr = MatCreate(comm,&A);CHKERRQ(ierr);
864   PetscValidLogicalCollectiveInt(A,spacedim,6);
865   PetscValidRealPointer(coords_target,7);
866   PetscValidRealPointer(coords_source,8);
867   if (!kernelctx) PetscValidFunction(kernel,9);
868   if (!kernel)    PetscValidPointer(kernelctx,10);
869   ierr = MatSetSizes(A,m,n,M,N);CHKERRQ(ierr);
870   ierr = MatSetType(A,MATHTOOL);CHKERRQ(ierr);
871   ierr = MatSetUp(A);CHKERRQ(ierr);
872   a            = (Mat_Htool*)A->data;
873   a->dim       = spacedim;
874   a->s         = 1.0;
875   a->kernel    = kernel;
876   a->kernelctx = kernelctx;
877   ierr = PetscCalloc1(A->rmap->N*spacedim,&a->gcoords_target);CHKERRQ(ierr);
878   ierr = PetscArraycpy(a->gcoords_target+A->rmap->rstart*spacedim,coords_target,A->rmap->n*spacedim);CHKERRQ(ierr);
879   ierr = MPIU_Allreduce(MPI_IN_PLACE,a->gcoords_target,A->rmap->N*spacedim,MPIU_REAL,MPI_SUM,PetscObjectComm((PetscObject)A));CHKERRMPI(ierr); /* global target coordinates */
880   if (coords_target != coords_source) {
881     ierr = PetscCalloc1(A->cmap->N*spacedim,&a->gcoords_source);CHKERRQ(ierr);
882     ierr = PetscArraycpy(a->gcoords_source+A->cmap->rstart*spacedim,coords_source,A->cmap->n*spacedim);CHKERRQ(ierr);
883     ierr = MPIU_Allreduce(MPI_IN_PLACE,a->gcoords_source,A->cmap->N*spacedim,MPIU_REAL,MPI_SUM,PetscObjectComm((PetscObject)A));CHKERRMPI(ierr); /* global source coordinates */
884   } else a->gcoords_source = a->gcoords_target;
885   ierr = PetscCalloc2(A->cmap->N,&a->work_source,A->rmap->N,&a->work_target);CHKERRQ(ierr);
886   *B = A;
887   PetscFunctionReturn(0);
888 }
889 
890 /*MC
891      MATHTOOL = "htool" - A matrix type for hierarchical matrices using the Htool package.
892 
893   Use ./configure --download-htool to install PETSc to use Htool.
894 
895    Options Database Keys:
896 .     -mat_type htool - matrix type to "htool" during a call to MatSetFromOptions()
897 
898    Level: beginner
899 
900 .seealso: MATH2OPUS, MATDENSE, MatCreateHtoolFromKernel(), MatHtoolSetKernel()
901 M*/
902 PETSC_EXTERN PetscErrorCode MatCreate_Htool(Mat A)
903 {
904   Mat_Htool      *a;
905   PetscErrorCode ierr;
906 
907   PetscFunctionBegin;
908   ierr = PetscNewLog(A,&a);CHKERRQ(ierr);
909   A->data = (void*)a;
910   ierr = PetscObjectChangeTypeName((PetscObject)A,MATHTOOL);CHKERRQ(ierr);
911   ierr = PetscMemzero(A->ops,sizeof(struct _MatOps));CHKERRQ(ierr);
912   A->ops->getdiagonal       = MatGetDiagonal_Htool;
913   A->ops->getdiagonalblock  = MatGetDiagonalBlock_Htool;
914   A->ops->mult              = MatMult_Htool;
915   A->ops->multadd           = MatMultAdd_Htool;
916   A->ops->increaseoverlap   = MatIncreaseOverlap_Htool;
917   A->ops->createsubmatrices = MatCreateSubMatrices_Htool;
918   A->ops->transpose         = MatTranspose_Htool;
919   A->ops->destroy           = MatDestroy_Htool;
920   A->ops->view              = MatView_Htool;
921   A->ops->setfromoptions    = MatSetFromOptions_Htool;
922   A->ops->scale             = MatScale_Htool;
923   A->ops->getrow            = MatGetRow_Htool;
924   A->ops->restorerow        = MatRestoreRow_Htool;
925   A->ops->assemblyend       = MatAssemblyEnd_Htool;
926   a->dim                    = 0;
927   a->gcoords_target         = NULL;
928   a->gcoords_source         = NULL;
929   a->s                      = 1.0;
930   a->bs[0]                  = 10;
931   a->bs[1]                  = 1000000;
932   a->epsilon                = PetscSqrtReal(PETSC_SMALL);
933   a->eta                    = 10.0;
934   a->depth[0]               = 0;
935   a->depth[1]               = 0;
936   a->compressor             = MAT_HTOOL_COMPRESSOR_SYMPARTIAL_ACA;
937   ierr = PetscObjectComposeFunction((PetscObject)A,"MatProductSetFromOptions_htool_seqdense_C",MatProductSetFromOptions_Htool);CHKERRQ(ierr);
938   ierr = PetscObjectComposeFunction((PetscObject)A,"MatProductSetFromOptions_htool_mpidense_C",MatProductSetFromOptions_Htool);CHKERRQ(ierr);
939   ierr = PetscObjectComposeFunction((PetscObject)A,"MatConvert_htool_seqdense_C",MatConvert_Htool_Dense);CHKERRQ(ierr);
940   ierr = PetscObjectComposeFunction((PetscObject)A,"MatConvert_htool_mpidense_C",MatConvert_Htool_Dense);CHKERRQ(ierr);
941   ierr = PetscObjectComposeFunction((PetscObject)A,"MatHtoolGetHierarchicalMat_C",MatHtoolGetHierarchicalMat_Htool);CHKERRQ(ierr);
942   ierr = PetscObjectComposeFunction((PetscObject)A,"MatHtoolSetKernel_C",MatHtoolSetKernel_Htool);CHKERRQ(ierr);
943   ierr = PetscObjectComposeFunction((PetscObject)A,"MatHtoolGetPermutationSource_C",MatHtoolGetPermutationSource_Htool);CHKERRQ(ierr);
944   ierr = PetscObjectComposeFunction((PetscObject)A,"MatHtoolGetPermutationTarget_C",MatHtoolGetPermutationTarget_Htool);CHKERRQ(ierr);
945   ierr = PetscObjectComposeFunction((PetscObject)A,"MatHtoolUsePermutation_C",MatHtoolUsePermutation_Htool);CHKERRQ(ierr);
946   PetscFunctionReturn(0);
947 }
948