xref: /petsc/src/ksp/pc/impls/telescope/telescope_dmda.c (revision f441ce4e2d98821aaabd56ae4c0a2bf92ac5ef63)
1 
2 #include <petsc/private/pcimpl.h>
3 #include <petscksp.h>           /*I "petscksp.h" I*/
4 #include <petscdm.h>
5 #include <petscdmda.h>
6 
7 #include "telescope.h"
8 
9 #undef __FUNCT__
10 #define __FUNCT__ "_DMDADetermineRankFromGlobalIJK"
11 PetscErrorCode _DMDADetermineRankFromGlobalIJK(PetscInt dim,PetscInt i,PetscInt j,PetscInt k,
12                                                PetscInt Mp,PetscInt Np,PetscInt Pp,
13                                                PetscInt start_i[],PetscInt start_j[],PetscInt start_k[],
14                                                PetscInt span_i[],PetscInt span_j[],PetscInt span_k[],
15                                                PetscMPIInt *_pi,PetscMPIInt *_pj,PetscMPIInt *_pk,PetscMPIInt *rank_re)
16 {
17   PetscInt pi,pj,pk,n;
18 
19   PetscFunctionBegin;
20   pi = pj = pk = -1;
21   if (_pi) {
22     for (n=0; n<Mp; n++) {
23       if ( (i >= start_i[n]) && (i < start_i[n]+span_i[n]) ) {
24         pi = n;
25         break;
26       }
27     }
28     if (pi == -1) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_USER,"[dmda-ijk] pi cannot be determined : range %D, val %D",Mp,i);
29     *_pi = pi;
30   }
31 
32   if (_pj) {
33     for (n=0; n<Np; n++) {
34       if ( (j >= start_j[n]) && (j < start_j[n]+span_j[n]) ) {
35         pj = n;
36         break;
37       }
38     }
39     if (pj == -1) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_USER,"[dmda-ijk] pj cannot be determined : range %D, val %D",Np,j);
40     *_pj = pj;
41   }
42 
43   if (_pk) {
44     for (n=0; n<Pp; n++) {
45       if ( (k >= start_k[n]) && (k < start_k[n]+span_k[n]) ) {
46         pk = n;
47         break;
48       }
49     }
50     if (pk == -1) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_USER,"[dmda-ijk] pk cannot be determined : range %D, val %D",Pp,k);
51     *_pk = pk;
52   }
53 
54   switch (dim) {
55     case 1:
56       *rank_re = pi;
57       break;
58     case 2:
59       *rank_re = pi + pj * Mp;
60       break;
61     case 3:
62       *rank_re = pi + pj * Mp + pk * (Mp*Np);
63       break;
64   }
65   PetscFunctionReturn(0);
66 }
67 
68 #undef __FUNCT__
69 #define __FUNCT__ "_DMDADetermineGlobalS0"
70 PetscErrorCode _DMDADetermineGlobalS0(PetscInt dim,PetscMPIInt rank_re,PetscInt Mp_re,PetscInt Np_re,PetscInt Pp_re,
71                                       PetscInt range_i_re[],PetscInt range_j_re[],PetscInt range_k_re[],PetscInt *s0)
72 {
73   PetscInt i,j,k,start_IJK = 0;
74   PetscInt rank_ijk;
75 
76   PetscFunctionBegin;
77   switch (dim) {
78     case 1:
79       for (i=0; i<Mp_re; i++) {
80         rank_ijk = i;
81         if (rank_ijk < rank_re) {
82           start_IJK += range_i_re[i];
83         }
84       }
85       break;
86     case 2:
87       for (j=0; j<Np_re; j++) {
88         for (i=0; i<Mp_re; i++) {
89           rank_ijk = i + j*Mp_re;
90           if (rank_ijk < rank_re) {
91             start_IJK += range_i_re[i]*range_j_re[j];
92           }
93         }
94       }
95       break;
96     case 3:
97       for (k=0; k<Pp_re; k++) {
98         for (j=0; j<Np_re; j++) {
99           for (i=0; i<Mp_re; i++) {
100             rank_ijk = i + j*Mp_re + k*Mp_re*Np_re;
101             if (rank_ijk < rank_re) {
102               start_IJK += range_i_re[i]*range_j_re[j]*range_k_re[k];
103             }
104           }
105         }
106       }
107       break;
108   }
109   *s0 = start_IJK;
110   PetscFunctionReturn(0);
111 }
112 
113 #undef __FUNCT__
114 #define __FUNCT__ "PCTelescopeSetUp_dmda_repart_coors2d"
115 PetscErrorCode PCTelescopeSetUp_dmda_repart_coors2d(PetscSubcomm psubcomm,DM dm,DM subdm)
116 {
117   PetscErrorCode ierr;
118   DM             cdm;
119   Vec            coor,coor_natural,perm_coors;
120   PetscInt       i,j,si,sj,ni,nj,M,N,Ml,Nl,c,nidx;
121   PetscInt       *fine_indices;
122   IS             is_fine,is_local;
123   VecScatter     sctx;
124 
125   PetscFunctionBegin;
126   ierr = DMGetCoordinates(dm,&coor);CHKERRQ(ierr);
127   if (!coor) return(0);
128   if (isActiveRank(psubcomm)) {
129     ierr = DMDASetUniformCoordinates(subdm,0.0,1.0,0.0,1.0,0.0,1.0);CHKERRQ(ierr);
130   }
131   /* Get the coordinate vector from the distributed array */
132   ierr = DMGetCoordinateDM(dm,&cdm);CHKERRQ(ierr);
133   ierr = DMDACreateNaturalVector(cdm,&coor_natural);CHKERRQ(ierr);
134 
135   ierr = DMDAGlobalToNaturalBegin(cdm,coor,INSERT_VALUES,coor_natural);CHKERRQ(ierr);
136   ierr = DMDAGlobalToNaturalEnd(cdm,coor,INSERT_VALUES,coor_natural);CHKERRQ(ierr);
137 
138   /* get indices of the guys I want to grab */
139   ierr = DMDAGetInfo(dm,NULL,&M,&N,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
140   if (isActiveRank(psubcomm)) {
141     ierr = DMDAGetCorners(subdm,&si,&sj,NULL,&ni,&nj,NULL);CHKERRQ(ierr);
142     Ml = ni;
143     Nl = nj;
144   } else {
145     Ml = Nl = 0;
146   }
147 
148   ierr = PetscMalloc1(Ml*Nl*2,&fine_indices);CHKERRQ(ierr);
149   c = 0;
150   if (isActiveRank(psubcomm)) {
151     for (j=sj; j<sj+nj; j++) {
152       for (i=si; i<si+ni; i++) {
153         nidx = (i) + (j)*M;
154         fine_indices[c  ] = 2 * nidx     ;
155         fine_indices[c+1] = 2 * nidx + 1 ;
156         c = c + 2;
157       }
158     }
159     if (c != Ml*Nl*2) SETERRQ3(PETSC_COMM_SELF,PETSC_ERR_PLIB,"c %D should equal 2 * Ml %D * Nl %D",c,Ml,Nl);
160   }
161 
162   /* generate scatter */
163   ierr = ISCreateGeneral(PetscObjectComm((PetscObject)dm),Ml*Nl*2,fine_indices,PETSC_USE_POINTER,&is_fine);CHKERRQ(ierr);
164   ierr = ISCreateStride(PETSC_COMM_SELF,Ml*Nl*2,0,1,&is_local);CHKERRQ(ierr);
165 
166   /* scatter */
167   ierr = VecCreate(PETSC_COMM_SELF,&perm_coors);CHKERRQ(ierr);
168   ierr = VecSetSizes(perm_coors,PETSC_DECIDE,Ml*Nl*2);CHKERRQ(ierr);
169   ierr = VecSetType(perm_coors,VECSEQ);CHKERRQ(ierr);
170 
171   ierr = VecScatterCreate(coor_natural,is_fine,perm_coors,is_local,&sctx);CHKERRQ(ierr);
172   ierr = VecScatterBegin(sctx,coor_natural,perm_coors,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
173   ierr = VecScatterEnd(  sctx,coor_natural,perm_coors,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
174   /* access */
175   if (isActiveRank(psubcomm)) {
176     Vec               _coors;
177     const PetscScalar *LA_perm;
178     PetscScalar       *LA_coors;
179 
180     ierr = DMGetCoordinates(subdm,&_coors);CHKERRQ(ierr);
181     ierr = VecGetArrayRead(perm_coors,&LA_perm);CHKERRQ(ierr);
182     ierr = VecGetArray(_coors,&LA_coors);CHKERRQ(ierr);
183     for (i=0; i<Ml*Nl*2; i++) {
184       LA_coors[i] = LA_perm[i];
185     }
186     ierr = VecRestoreArray(_coors,&LA_coors);CHKERRQ(ierr);
187     ierr = VecRestoreArrayRead(perm_coors,&LA_perm);CHKERRQ(ierr);
188   }
189 
190   /* update local coords */
191   if (isActiveRank(psubcomm)) {
192     DM  _dmc;
193     Vec _coors,_coors_local;
194     ierr = DMGetCoordinateDM(subdm,&_dmc);CHKERRQ(ierr);
195     ierr = DMGetCoordinates(subdm,&_coors);CHKERRQ(ierr);
196     ierr = DMGetCoordinatesLocal(subdm,&_coors_local);CHKERRQ(ierr);
197     ierr = DMGlobalToLocalBegin(_dmc,_coors,INSERT_VALUES,_coors_local);CHKERRQ(ierr);
198     ierr = DMGlobalToLocalEnd(_dmc,_coors,INSERT_VALUES,_coors_local);CHKERRQ(ierr);
199   }
200   ierr = VecScatterDestroy(&sctx);CHKERRQ(ierr);
201   ierr = ISDestroy(&is_fine);CHKERRQ(ierr);
202   ierr = PetscFree(fine_indices);CHKERRQ(ierr);
203   ierr = ISDestroy(&is_local);CHKERRQ(ierr);
204   ierr = VecDestroy(&perm_coors);CHKERRQ(ierr);
205   ierr = VecDestroy(&coor_natural);CHKERRQ(ierr);
206   PetscFunctionReturn(0);
207 }
208 
209 #undef __FUNCT__
210 #define __FUNCT__ "PCTelescopeSetUp_dmda_repart_coors3d"
211 PetscErrorCode PCTelescopeSetUp_dmda_repart_coors3d(PetscSubcomm psubcomm,DM dm,DM subdm)
212 {
213   PetscErrorCode ierr;
214   DM             cdm;
215   Vec            coor,coor_natural,perm_coors;
216   PetscInt       i,j,k,si,sj,sk,ni,nj,nk,M,N,P,Ml,Nl,Pl,c,nidx;
217   PetscInt       *fine_indices;
218   IS             is_fine,is_local;
219   VecScatter     sctx;
220 
221   PetscFunctionBegin;
222   ierr = DMGetCoordinates(dm,&coor);CHKERRQ(ierr);
223   if (!coor) PetscFunctionReturn(0);
224 
225   if (isActiveRank(psubcomm)) {
226     ierr = DMDASetUniformCoordinates(subdm,0.0,1.0,0.0,1.0,0.0,1.0);CHKERRQ(ierr);
227   }
228 
229   /* Get the coordinate vector from the distributed array */
230   ierr = DMGetCoordinateDM(dm,&cdm);CHKERRQ(ierr);
231   ierr = DMDACreateNaturalVector(cdm,&coor_natural);CHKERRQ(ierr);
232   ierr = DMDAGlobalToNaturalBegin(cdm,coor,INSERT_VALUES,coor_natural);CHKERRQ(ierr);
233   ierr = DMDAGlobalToNaturalEnd(cdm,coor,INSERT_VALUES,coor_natural);CHKERRQ(ierr);
234 
235   /* get indices of the guys I want to grab */
236   ierr = DMDAGetInfo(dm,NULL,&M,&N,&P,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
237 
238   if (isActiveRank(psubcomm)) {
239     ierr = DMDAGetCorners(subdm,&si,&sj,&sk,&ni,&nj,&nk);CHKERRQ(ierr);
240 
241     Ml = ni - si;
242     Nl = nj - sj;
243     Pl = nk - sk;
244   } else {
245     Ml = Nl = Pl = 0;
246   }
247 
248   ierr = PetscMalloc1(Ml*Nl*Pl*3,&fine_indices);CHKERRQ(ierr);
249 
250   c = 0;
251   if (isActiveRank(psubcomm)) {
252     for (k=sk; k<sk+nk; k++) {
253       for (j=sj; j<sj+nj; j++) {
254         for (i=si; i<si+ni; i++) {
255           nidx = (i) + (j)*M + (k)*M*N;
256           fine_indices[c  ] = 3 * nidx     ;
257           fine_indices[c+1] = 3 * nidx + 1 ;
258           fine_indices[c+2] = 3 * nidx + 2 ;
259           c = c + 3;
260         }
261       }
262     }
263   }
264 
265   /* generate scatter */
266   ierr = ISCreateGeneral(PetscObjectComm((PetscObject)dm),Ml*Nl*Pl*3,fine_indices,PETSC_USE_POINTER,&is_fine);CHKERRQ(ierr);
267   ierr = ISCreateStride(PETSC_COMM_SELF,Ml*Nl*Pl*3,0,1,&is_local);CHKERRQ(ierr);
268 
269   /* scatter */
270   ierr = VecCreate(PETSC_COMM_SELF,&perm_coors);CHKERRQ(ierr);
271   ierr = VecSetSizes(perm_coors,PETSC_DECIDE,Ml*Nl*Pl*3);CHKERRQ(ierr);
272   ierr = VecSetType(perm_coors,VECSEQ);CHKERRQ(ierr);
273   ierr = VecScatterCreate(coor_natural,is_fine,perm_coors,is_local,&sctx);CHKERRQ(ierr);
274   ierr = VecScatterBegin(sctx,coor_natural,perm_coors,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
275   ierr = VecScatterEnd(  sctx,coor_natural,perm_coors,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
276 
277   /* access */
278   if (isActiveRank(psubcomm)) {
279     Vec               _coors;
280     const PetscScalar *LA_perm;
281     PetscScalar       *LA_coors;
282 
283     ierr = DMGetCoordinates(subdm,&_coors);CHKERRQ(ierr);
284     ierr = VecGetArrayRead(perm_coors,&LA_perm);CHKERRQ(ierr);
285     ierr = VecGetArray(_coors,&LA_coors);CHKERRQ(ierr);
286     for (i=0; i<Ml*Nl*Pl*3; i++) {
287       LA_coors[i] = LA_perm[i];
288     }
289     ierr = VecRestoreArray(_coors,&LA_coors);CHKERRQ(ierr);
290     ierr = VecRestoreArrayRead(perm_coors,&LA_perm);CHKERRQ(ierr);
291   }
292 
293   /* update local coords */
294   if (isActiveRank(psubcomm)) {
295     DM  _dmc;
296     Vec _coors,_coors_local;
297 
298     ierr = DMGetCoordinateDM(subdm,&_dmc);CHKERRQ(ierr);
299     ierr = DMGetCoordinates(subdm,&_coors);CHKERRQ(ierr);
300     ierr = DMGetCoordinatesLocal(subdm,&_coors_local);CHKERRQ(ierr);
301     ierr = DMGlobalToLocalBegin(_dmc,_coors,INSERT_VALUES,_coors_local);CHKERRQ(ierr);
302     ierr = DMGlobalToLocalEnd(_dmc,_coors,INSERT_VALUES,_coors_local);CHKERRQ(ierr);
303   }
304 
305   ierr = VecScatterDestroy(&sctx);CHKERRQ(ierr);
306   ierr = ISDestroy(&is_fine);CHKERRQ(ierr);
307   ierr = PetscFree(fine_indices);CHKERRQ(ierr);
308   ierr = ISDestroy(&is_local);CHKERRQ(ierr);
309   ierr = VecDestroy(&perm_coors);CHKERRQ(ierr);
310   ierr = VecDestroy(&coor_natural);CHKERRQ(ierr);
311   PetscFunctionReturn(0);
312 }
313 
314 #undef __FUNCT__
315 #define __FUNCT__ "PCTelescopeSetUp_dmda_repart_coors"
316 PetscErrorCode PCTelescopeSetUp_dmda_repart_coors(PC pc,PC_Telescope sred,PC_Telescope_DMDACtx *ctx)
317 {
318   PetscInt       dim;
319   DM             dm,subdm;
320   PetscSubcomm   psubcomm;
321   MPI_Comm       comm;
322   Vec            coor;
323   PetscErrorCode ierr;
324 
325   PetscFunctionBegin;
326   ierr = PCGetDM(pc,&dm);CHKERRQ(ierr);
327   ierr = DMGetCoordinates(dm,&coor);CHKERRQ(ierr);
328   if (!coor) PetscFunctionReturn(0);
329   psubcomm = sred->psubcomm;
330   comm = PetscSubcommParent(psubcomm);
331   subdm = ctx->dmrepart;
332 
333 
334   ierr = PetscInfo(pc,"PCTelescope: setting up the coordinates (DMDA)\n");CHKERRQ(ierr);
335   ierr = DMDAGetInfo(dm,&dim,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
336   switch (dim) {
337   case 1: SETERRQ(comm,PETSC_ERR_SUP,"Telescope: DMDA (1D) repartitioning not provided");
338     break;
339   case 2: PCTelescopeSetUp_dmda_repart_coors2d(psubcomm,dm,subdm);
340     break;
341   case 3: PCTelescopeSetUp_dmda_repart_coors3d(psubcomm,dm,subdm);
342     break;
343   }
344   PetscFunctionReturn(0);
345 }
346 
347 /* setup repartitioned dm */
348 #undef __FUNCT__
349 #define __FUNCT__ "PCTelescopeSetUp_dmda_repart"
350 PetscErrorCode PCTelescopeSetUp_dmda_repart(PC pc,PC_Telescope sred,PC_Telescope_DMDACtx *ctx)
351 {
352   PetscErrorCode  ierr;
353   DM              dm;
354   PetscInt        dim,nx,ny,nz,ndof,nsw,sum,k;
355   DMBoundaryType  bx,by,bz;
356   DMDAStencilType stencil;
357   const PetscInt  *_range_i_re;
358   const PetscInt  *_range_j_re;
359   const PetscInt  *_range_k_re;
360   DMDAInterpolationType itype;
361   PetscInt              refine_x,refine_y,refine_z;
362   MPI_Comm              comm,subcomm;
363   const char            *prefix;
364 
365   PetscFunctionBegin;
366   comm = PetscSubcommParent(sred->psubcomm);
367   subcomm = PetscSubcommChild(sred->psubcomm);
368   ierr = PCGetDM(pc,&dm);CHKERRQ(ierr);
369 
370   ierr = DMDAGetInfo(dm,&dim,&nx,&ny,&nz,NULL,NULL,NULL,&ndof,&nsw,&bx,&by,&bz,&stencil);CHKERRQ(ierr);
371   ierr = DMDAGetInterpolationType(dm,&itype);CHKERRQ(ierr);
372   ierr = DMDAGetRefinementFactor(dm,&refine_x,&refine_y,&refine_z);CHKERRQ(ierr);
373 
374   ctx->dmrepart = NULL;
375   _range_i_re = _range_j_re = _range_k_re = NULL;
376   /* Create DMDA on the child communicator */
377   if (isActiveRank(sred->psubcomm)) {
378     switch (dim) {
379     case 1:
380       ierr = PetscInfo(pc,"PCTelescope: setting up the DMDA on comm subset (1D)\n");CHKERRQ(ierr);
381       /*ierr = DMDACreate1d(subcomm,bx,nx,ndof,nsw,NULL,&ctx->dmrepart);CHKERRQ(ierr);*/
382       ny = nz = 1;
383       by = bz = DM_BOUNDARY_NONE;
384       break;
385     case 2:
386       ierr = PetscInfo(pc,"PCTelescope: setting up the DMDA on comm subset (2D)\n");CHKERRQ(ierr);
387       /*ierr = DMDACreate2d(subcomm,bx,by,stencil,nx,ny, PETSC_DECIDE,PETSC_DECIDE, ndof,nsw, NULL,NULL,&ctx->dmrepart);CHKERRQ(ierr);*/
388       nz = 1;
389       bz = DM_BOUNDARY_NONE;
390       break;
391     case 3:
392       ierr = PetscInfo(pc,"PCTelescope: setting up the DMDA on comm subset (3D)\n");CHKERRQ(ierr);
393       /*ierr = DMDACreate3d(subcomm,bx,by,bz,stencil,nx,ny,nz, PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE, ndof,nsw, NULL,NULL,NULL,&ctx->dmrepart);CHKERRQ(ierr);*/
394       break;
395     }
396     /*
397      The API DMDACreate1d(), DMDACreate2d(), DMDACreate3d() does not allow us to set/append
398      a unique option prefix for the DM, thus I prefer to expose the contents of these API's here.
399      This allows users to control the partitioning of the subDM.
400     */
401     ierr = DMDACreate(subcomm,&ctx->dmrepart);CHKERRQ(ierr);
402     /* Set unique option prefix name */
403     ierr = DMGetOptionsPrefix(dm,&prefix);CHKERRQ(ierr);
404     ierr = DMSetOptionsPrefix(ctx->dmrepart,prefix);CHKERRQ(ierr);
405     ierr = DMAppendOptionsPrefix(ctx->dmrepart,"repart_");CHKERRQ(ierr);
406     /* standard setup from DMDACreate{1,2,3}d() */
407     ierr = DMSetDimension(ctx->dmrepart,dim);CHKERRQ(ierr);
408     ierr = DMDASetSizes(ctx->dmrepart,nx,ny,nz);CHKERRQ(ierr);
409     ierr = DMDASetNumProcs(ctx->dmrepart,PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE);CHKERRQ(ierr);
410     ierr = DMDASetBoundaryType(ctx->dmrepart,bx,by,bz);CHKERRQ(ierr);
411     ierr = DMDASetDof(ctx->dmrepart,ndof);CHKERRQ(ierr);
412     ierr = DMDASetStencilType(ctx->dmrepart,stencil);CHKERRQ(ierr);
413     ierr = DMDASetStencilWidth(ctx->dmrepart,nsw);CHKERRQ(ierr);
414     ierr = DMDASetOwnershipRanges(ctx->dmrepart,NULL,NULL,NULL);CHKERRQ(ierr);
415     ierr = DMSetFromOptions(ctx->dmrepart);CHKERRQ(ierr);
416     ierr = DMSetUp(ctx->dmrepart);CHKERRQ(ierr);
417     /* Set refinement factors and interpolation type from the partent */
418     ierr = DMDASetRefinementFactor(ctx->dmrepart,refine_x,refine_y,refine_z);CHKERRQ(ierr);
419     ierr = DMDASetInterpolationType(ctx->dmrepart,itype);CHKERRQ(ierr);
420 
421     ierr = DMDAGetInfo(ctx->dmrepart,NULL,NULL,NULL,NULL,&ctx->Mp_re,&ctx->Np_re,&ctx->Pp_re,NULL,NULL,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
422     ierr = DMDAGetOwnershipRanges(ctx->dmrepart,&_range_i_re,&_range_j_re,&_range_k_re);CHKERRQ(ierr);
423   }
424 
425   /* generate ranges for repartitioned dm */
426   /* note - assume rank 0 always participates */
427   ierr = MPI_Bcast(&ctx->Mp_re,1,MPIU_INT,0,comm);CHKERRQ(ierr);
428   ierr = MPI_Bcast(&ctx->Np_re,1,MPIU_INT,0,comm);CHKERRQ(ierr);
429   ierr = MPI_Bcast(&ctx->Pp_re,1,MPIU_INT,0,comm);CHKERRQ(ierr);
430 
431   ierr = PetscCalloc1(ctx->Mp_re,&ctx->range_i_re);CHKERRQ(ierr);
432   ierr = PetscCalloc1(ctx->Np_re,&ctx->range_j_re);CHKERRQ(ierr);
433   ierr = PetscCalloc1(ctx->Pp_re,&ctx->range_k_re);CHKERRQ(ierr);
434 
435   if (_range_i_re) {ierr = PetscMemcpy(ctx->range_i_re,_range_i_re,sizeof(PetscInt)*ctx->Mp_re);CHKERRQ(ierr);}
436   if (_range_j_re) {ierr = PetscMemcpy(ctx->range_j_re,_range_j_re,sizeof(PetscInt)*ctx->Np_re);CHKERRQ(ierr);}
437   if (_range_k_re) {ierr = PetscMemcpy(ctx->range_k_re,_range_k_re,sizeof(PetscInt)*ctx->Pp_re);CHKERRQ(ierr);}
438 
439   ierr = MPI_Bcast(ctx->range_i_re,ctx->Mp_re,MPIU_INT,0,comm);CHKERRQ(ierr);
440   ierr = MPI_Bcast(ctx->range_j_re,ctx->Np_re,MPIU_INT,0,comm);CHKERRQ(ierr);
441   ierr = MPI_Bcast(ctx->range_k_re,ctx->Pp_re,MPIU_INT,0,comm);CHKERRQ(ierr);
442 
443   ierr = PetscMalloc1(ctx->Mp_re,&ctx->start_i_re);CHKERRQ(ierr);
444   ierr = PetscMalloc1(ctx->Np_re,&ctx->start_j_re);CHKERRQ(ierr);
445   ierr = PetscMalloc1(ctx->Pp_re,&ctx->start_k_re);CHKERRQ(ierr);
446 
447   sum = 0;
448   for (k=0; k<ctx->Mp_re; k++) {
449     ctx->start_i_re[k] = sum;
450     sum += ctx->range_i_re[k];
451   }
452 
453   sum = 0;
454   for (k=0; k<ctx->Np_re; k++) {
455     ctx->start_j_re[k] = sum;
456     sum += ctx->range_j_re[k];
457   }
458 
459   sum = 0;
460   for (k=0; k<ctx->Pp_re; k++) {
461     ctx->start_k_re[k] = sum;
462     sum += ctx->range_k_re[k];
463   }
464 
465   /* attach dm to ksp on sub communicator */
466   if (isActiveRank(sred->psubcomm)) {
467     ierr = KSPSetDM(sred->ksp,ctx->dmrepart);CHKERRQ(ierr);
468     ierr = KSPSetDMActive(sred->ksp,PETSC_FALSE);CHKERRQ(ierr);
469   }
470   PetscFunctionReturn(0);
471 }
472 
473 #undef __FUNCT__
474 #define __FUNCT__ "PCTelescopeSetUp_dmda_permutation_3d"
475 PetscErrorCode PCTelescopeSetUp_dmda_permutation_3d(PC pc,PC_Telescope sred,PC_Telescope_DMDACtx *ctx)
476 {
477   PetscErrorCode ierr;
478   DM             dm;
479   MPI_Comm       comm;
480   Mat            Pscalar,P;
481   PetscInt       ndof;
482   PetscInt       i,j,k,location,startI[3],endI[3],lenI[3],nx,ny,nz;
483   PetscInt       sr,er,Mr;
484   Vec            V;
485 
486   PetscFunctionBegin;
487   ierr = PetscInfo(pc,"PCTelescope: setting up the permutation matrix (DMDA-3D)\n");CHKERRQ(ierr);
488   ierr = PetscObjectGetComm((PetscObject)pc,&comm);CHKERRQ(ierr);
489 
490   ierr = PCGetDM(pc,&dm);CHKERRQ(ierr);
491   ierr = DMDAGetInfo(dm,NULL,&nx,&ny,&nz,NULL,NULL,NULL,&ndof,NULL,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
492 
493   ierr = DMGetGlobalVector(dm,&V);CHKERRQ(ierr);
494   ierr = VecGetSize(V,&Mr);CHKERRQ(ierr);
495   ierr = VecGetOwnershipRange(V,&sr,&er);CHKERRQ(ierr);
496   ierr = DMRestoreGlobalVector(dm,&V);CHKERRQ(ierr);
497   sr = sr / ndof;
498   er = er / ndof;
499   Mr = Mr / ndof;
500 
501   ierr = MatCreate(comm,&Pscalar);CHKERRQ(ierr);
502   ierr = MatSetSizes(Pscalar,(er-sr),(er-sr),Mr,Mr);CHKERRQ(ierr);
503   ierr = MatSetType(Pscalar,MATAIJ);CHKERRQ(ierr);
504   ierr = MatSeqAIJSetPreallocation(Pscalar,2,NULL);CHKERRQ(ierr);
505   ierr = MatMPIAIJSetPreallocation(Pscalar,2,NULL,2,NULL);CHKERRQ(ierr);
506 
507   ierr = DMDAGetCorners(dm,NULL,NULL,NULL,&lenI[0],&lenI[1],&lenI[2]);CHKERRQ(ierr);
508   ierr = DMDAGetCorners(dm,&startI[0],&startI[1],&startI[2],&endI[0],&endI[1],&endI[2]);CHKERRQ(ierr);
509   endI[0] += startI[0];
510   endI[1] += startI[1];
511   endI[2] += startI[2];
512 
513   for (k=startI[2]; k<endI[2]; k++) {
514     for (j=startI[1]; j<endI[1]; j++) {
515       for (i=startI[0]; i<endI[0]; i++) {
516         PetscMPIInt rank_ijk_re,rank_reI[3];
517         PetscInt    s0_re;
518         PetscInt    ii,jj,kk,local_ijk_re,mapped_ijk;
519         PetscInt    lenI_re[3];
520 
521         location = (i - startI[0]) + (j - startI[1])*lenI[0] + (k - startI[2])*lenI[0]*lenI[1];
522         ierr = _DMDADetermineRankFromGlobalIJK(3,i,j,k,   ctx->Mp_re,ctx->Np_re,ctx->Pp_re,
523                                                ctx->start_i_re,ctx->start_j_re,ctx->start_k_re,
524                                                ctx->range_i_re,ctx->range_j_re,ctx->range_k_re,
525                                                &rank_reI[0],&rank_reI[1],&rank_reI[2],&rank_ijk_re);CHKERRQ(ierr);
526         ierr = _DMDADetermineGlobalS0(3,rank_ijk_re, ctx->Mp_re,ctx->Np_re,ctx->Pp_re, ctx->range_i_re,ctx->range_j_re,ctx->range_k_re, &s0_re);CHKERRQ(ierr);
527         ii = i - ctx->start_i_re[ rank_reI[0] ];
528         if (ii < 0) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"[dmdarepart-perm3d] index error ii");
529         jj = j - ctx->start_j_re[ rank_reI[1] ];
530         if (jj < 0) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"[dmdarepart-perm3d] index error jj");
531         kk = k - ctx->start_k_re[ rank_reI[2] ];
532         if (kk < 0) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"[dmdarepart-perm3d] index error kk");
533         lenI_re[0] = ctx->range_i_re[ rank_reI[0] ];
534         lenI_re[1] = ctx->range_j_re[ rank_reI[1] ];
535         lenI_re[2] = ctx->range_k_re[ rank_reI[2] ];
536         local_ijk_re = ii + jj * lenI_re[0] + kk * lenI_re[0] * lenI_re[1];
537         mapped_ijk = s0_re + local_ijk_re;
538         ierr = MatSetValue(Pscalar,sr+location,mapped_ijk,1.0,INSERT_VALUES);CHKERRQ(ierr);
539       }
540     }
541   }
542   ierr = MatAssemblyBegin(Pscalar,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
543   ierr = MatAssemblyEnd(Pscalar,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
544   ierr = MatCreateMAIJ(Pscalar,ndof,&P);CHKERRQ(ierr);
545   ierr = MatDestroy(&Pscalar);CHKERRQ(ierr);
546   ctx->permutation = P;
547   PetscFunctionReturn(0);
548 }
549 
550 #undef __FUNCT__
551 #define __FUNCT__ "PCTelescopeSetUp_dmda_permutation_2d"
552 PetscErrorCode PCTelescopeSetUp_dmda_permutation_2d(PC pc,PC_Telescope sred,PC_Telescope_DMDACtx *ctx)
553 {
554   PetscErrorCode ierr;
555   DM             dm;
556   MPI_Comm       comm;
557   Mat            Pscalar,P;
558   PetscInt       ndof;
559   PetscInt       i,j,location,startI[2],endI[2],lenI[2],nx,ny,nz;
560   PetscInt       sr,er,Mr;
561   Vec            V;
562 
563   PetscFunctionBegin;
564   ierr = PetscInfo(pc,"PCTelescope: setting up the permutation matrix (DMDA-2D)\n");CHKERRQ(ierr);
565   ierr = PetscObjectGetComm((PetscObject)pc,&comm);CHKERRQ(ierr);
566   ierr = PCGetDM(pc,&dm);CHKERRQ(ierr);
567   ierr = DMDAGetInfo(dm,NULL,&nx,&ny,&nz,NULL,NULL,NULL,&ndof,NULL,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
568   ierr = DMGetGlobalVector(dm,&V);CHKERRQ(ierr);
569   ierr = VecGetSize(V,&Mr);CHKERRQ(ierr);
570   ierr = VecGetOwnershipRange(V,&sr,&er);CHKERRQ(ierr);
571   ierr = DMRestoreGlobalVector(dm,&V);CHKERRQ(ierr);
572   sr = sr / ndof;
573   er = er / ndof;
574   Mr = Mr / ndof;
575 
576   ierr = MatCreate(comm,&Pscalar);CHKERRQ(ierr);
577   ierr = MatSetSizes(Pscalar,(er-sr),(er-sr),Mr,Mr);CHKERRQ(ierr);
578   ierr = MatSetType(Pscalar,MATAIJ);CHKERRQ(ierr);
579   ierr = MatSeqAIJSetPreallocation(Pscalar,2,NULL);CHKERRQ(ierr);
580   ierr = MatMPIAIJSetPreallocation(Pscalar,2,NULL,2,NULL);CHKERRQ(ierr);
581 
582   ierr = DMDAGetCorners(dm,NULL,NULL,NULL,&lenI[0],&lenI[1],NULL);CHKERRQ(ierr);
583   ierr = DMDAGetCorners(dm,&startI[0],&startI[1],NULL,&endI[0],&endI[1],NULL);CHKERRQ(ierr);
584   endI[0] += startI[0];
585   endI[1] += startI[1];
586 
587   for (j=startI[1]; j<endI[1]; j++) {
588     for (i=startI[0]; i<endI[0]; i++) {
589       PetscMPIInt rank_ijk_re,rank_reI[3];
590       PetscInt    s0_re;
591       PetscInt    ii,jj,local_ijk_re,mapped_ijk;
592       PetscInt    lenI_re[3];
593 
594       location = (i - startI[0]) + (j - startI[1])*lenI[0];
595       ierr = _DMDADetermineRankFromGlobalIJK(2,i,j,0,   ctx->Mp_re,ctx->Np_re,ctx->Pp_re,
596                                              ctx->start_i_re,ctx->start_j_re,ctx->start_k_re,
597                                              ctx->range_i_re,ctx->range_j_re,ctx->range_k_re,
598                                              &rank_reI[0],&rank_reI[1],NULL,&rank_ijk_re);CHKERRQ(ierr);
599 
600       ierr = _DMDADetermineGlobalS0(2,rank_ijk_re, ctx->Mp_re,ctx->Np_re,ctx->Pp_re, ctx->range_i_re,ctx->range_j_re,ctx->range_k_re, &s0_re);CHKERRQ(ierr);
601 
602       ii = i - ctx->start_i_re[ rank_reI[0] ];
603       if (ii < 0) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"[dmdarepart-perm2d] index error ii");
604       jj = j - ctx->start_j_re[ rank_reI[1] ];
605       if (jj < 0) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"[dmdarepart-perm2d] index error jj");
606 
607       lenI_re[0] = ctx->range_i_re[ rank_reI[0] ];
608       lenI_re[1] = ctx->range_j_re[ rank_reI[1] ];
609       local_ijk_re = ii + jj * lenI_re[0];
610       mapped_ijk = s0_re + local_ijk_re;
611       ierr = MatSetValue(Pscalar,sr+location,mapped_ijk,1.0,INSERT_VALUES);CHKERRQ(ierr);
612     }
613   }
614   ierr = MatAssemblyBegin(Pscalar,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
615   ierr = MatAssemblyEnd(Pscalar,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
616   ierr = MatCreateMAIJ(Pscalar,ndof,&P);CHKERRQ(ierr);
617   ierr = MatDestroy(&Pscalar);CHKERRQ(ierr);
618   ctx->permutation = P;
619   PetscFunctionReturn(0);
620 }
621 
622 #undef __FUNCT__
623 #define __FUNCT__ "PCTelescopeSetUp_dmda_scatters"
624 PetscErrorCode PCTelescopeSetUp_dmda_scatters(PC pc,PC_Telescope sred,PC_Telescope_DMDACtx *ctx)
625 {
626   PetscErrorCode ierr;
627   Vec            xred,yred,xtmp,x,xp;
628   VecScatter     scatter;
629   IS             isin;
630   Mat            B;
631   PetscInt       m,bs,st,ed;
632   MPI_Comm       comm;
633 
634   PetscFunctionBegin;
635   ierr = PetscObjectGetComm((PetscObject)pc,&comm);CHKERRQ(ierr);
636   ierr = PCGetOperators(pc,NULL,&B);CHKERRQ(ierr);
637   ierr = MatCreateVecs(B,&x,NULL);CHKERRQ(ierr);
638   ierr = MatGetBlockSize(B,&bs);CHKERRQ(ierr);
639   ierr = VecDuplicate(x,&xp);CHKERRQ(ierr);
640   m = 0;
641   xred = NULL;
642   yred = NULL;
643   if (isActiveRank(sred->psubcomm)) {
644     ierr = DMCreateGlobalVector(ctx->dmrepart,&xred);CHKERRQ(ierr);
645     ierr = VecDuplicate(xred,&yred);CHKERRQ(ierr);
646     ierr = VecGetOwnershipRange(xred,&st,&ed);CHKERRQ(ierr);
647     ierr = ISCreateStride(comm,ed-st,st,1,&isin);CHKERRQ(ierr);
648     ierr = VecGetLocalSize(xred,&m);
649   } else {
650     ierr = VecGetOwnershipRange(x,&st,&ed);CHKERRQ(ierr);
651     ierr = ISCreateStride(comm,0,st,1,&isin);CHKERRQ(ierr);
652   }
653   ierr = ISSetBlockSize(isin,bs);CHKERRQ(ierr);
654   ierr = VecCreate(comm,&xtmp);CHKERRQ(ierr);
655   ierr = VecSetSizes(xtmp,m,PETSC_DECIDE);CHKERRQ(ierr);
656   ierr = VecSetBlockSize(xtmp,bs);CHKERRQ(ierr);
657   ierr = VecSetType(xtmp,((PetscObject)x)->type_name);CHKERRQ(ierr);
658   ierr = VecScatterCreate(x,isin,xtmp,NULL,&scatter);CHKERRQ(ierr);
659   sred->xred    = xred;
660   sred->yred    = yred;
661   sred->isin    = isin;
662   sred->scatter = scatter;
663   sred->xtmp    = xtmp;
664 
665   ctx->xp       = xp;
666   ierr = VecDestroy(&x);CHKERRQ(ierr);
667   PetscFunctionReturn(0);
668 }
669 
670 #undef __FUNCT__
671 #define __FUNCT__ "PCTelescopeSetUp_dmda"
672 PetscErrorCode PCTelescopeSetUp_dmda(PC pc,PC_Telescope sred)
673 {
674   PC_Telescope_DMDACtx *ctx;
675   PetscInt                 dim;
676   DM                       dm;
677   MPI_Comm                 comm;
678   PetscErrorCode           ierr;
679 
680   PetscFunctionBegin;
681   ierr = PetscInfo(pc,"PCTelescope: setup (DMDA)\n");CHKERRQ(ierr);
682   PetscMalloc1(1,&ctx);
683   PetscMemzero(ctx,sizeof(PC_Telescope_DMDACtx));
684   sred->dm_ctx = (void*)ctx;
685 
686   ierr = PetscObjectGetComm((PetscObject)pc,&comm);CHKERRQ(ierr);
687   ierr = PCGetDM(pc,&dm);CHKERRQ(ierr);
688   ierr = DMDAGetInfo(dm,&dim,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
689 
690   PCTelescopeSetUp_dmda_repart(pc,sred,ctx);
691   PCTelescopeSetUp_dmda_repart_coors(pc,sred,ctx);
692   switch (dim) {
693   case 1: SETERRQ(comm,PETSC_ERR_SUP,"Telescope: DMDA (1D) repartitioning not provided");
694     break;
695   case 2: ierr = PCTelescopeSetUp_dmda_permutation_2d(pc,sred,ctx);CHKERRQ(ierr);
696     break;
697   case 3: ierr = PCTelescopeSetUp_dmda_permutation_3d(pc,sred,ctx);CHKERRQ(ierr);
698     break;
699   }
700   ierr = PCTelescopeSetUp_dmda_scatters(pc,sred,ctx);CHKERRQ(ierr);
701   PetscFunctionReturn(0);
702 }
703 
704 #undef __FUNCT__
705 #define __FUNCT__ "PCTelescopeMatCreate_dmda"
706 PetscErrorCode PCTelescopeMatCreate_dmda(PC pc,PC_Telescope sred,MatReuse reuse,Mat *A)
707 {
708   PetscErrorCode ierr;
709   PC_Telescope_DMDACtx *ctx;
710   MPI_Comm       comm,subcomm;
711   Mat            Bperm,Bred,B,P;
712   PetscInt       nr,nc;
713   IS             isrow,iscol;
714   Mat            Blocal,*_Blocal;
715 
716   PetscFunctionBegin;
717   ierr = PetscInfo(pc,"PCTelescope: updating the redundant preconditioned operator (DMDA)\n");CHKERRQ(ierr);
718   ierr = PetscObjectGetComm((PetscObject)pc,&comm);CHKERRQ(ierr);
719     subcomm = PetscSubcommChild(sred->psubcomm);
720   ctx = (PC_Telescope_DMDACtx*)sred->dm_ctx;
721 
722   ierr = PCGetOperators(pc,NULL,&B);CHKERRQ(ierr);
723   ierr = MatGetSize(B,&nr,&nc);CHKERRQ(ierr);
724 
725   P = ctx->permutation;
726   ierr = MatPtAP(B,P,MAT_INITIAL_MATRIX,1.1,&Bperm);CHKERRQ(ierr);
727 
728   /* Get submatrices */
729   isrow = sred->isin;
730   ierr = ISCreateStride(comm,nc,0,1,&iscol);CHKERRQ(ierr);
731 
732   ierr = MatGetSubMatrices(Bperm,1,&isrow,&iscol,MAT_INITIAL_MATRIX,&_Blocal);CHKERRQ(ierr);
733   Blocal = *_Blocal;
734   Bred = NULL;
735   if (isActiveRank(sred->psubcomm)) {
736     PetscInt mm;
737 
738     if (reuse != MAT_INITIAL_MATRIX) {Bred = *A;}
739     ierr = MatGetSize(Blocal,&mm,NULL);CHKERRQ(ierr);
740     /* ierr = MatCreateMPIMatConcatenateSeqMat(subcomm,Blocal,PETSC_DECIDE,reuse,&Bred);CHKERRQ(ierr); */
741     ierr = MatCreateMPIMatConcatenateSeqMat(subcomm,Blocal,mm,reuse,&Bred);CHKERRQ(ierr);
742   }
743   *A = Bred;
744 
745   ierr = ISDestroy(&iscol);CHKERRQ(ierr);
746   ierr = MatDestroy(&Bperm);CHKERRQ(ierr);
747   ierr = MatDestroyMatrices(1,&_Blocal);CHKERRQ(ierr);
748   PetscFunctionReturn(0);
749 }
750 
751 #undef __FUNCT__
752 #define __FUNCT__ "PCTelescopeMatNullSpaceCreate_dmda"
753 PetscErrorCode PCTelescopeMatNullSpaceCreate_dmda(PC pc,PC_Telescope sred,Mat sub_mat)
754 {
755   PetscErrorCode   ierr;
756   MatNullSpace     nullspace,sub_nullspace;
757   Mat              A,B;
758   PetscBool        has_const;
759   PetscInt         i,k,n;
760   const Vec        *vecs;
761   Vec              *sub_vecs;
762   MPI_Comm         subcomm;
763   PC_Telescope_DMDACtx *ctx;
764 
765   PetscFunctionBegin;
766   ierr = PCGetOperators(pc,&A,&B);CHKERRQ(ierr);
767   ierr = MatGetNullSpace(B,&nullspace);CHKERRQ(ierr);
768   if (!nullspace) return(0);
769 
770   ierr = PetscInfo(pc,"PCTelescope: generating nullspace (DMDA)\n");CHKERRQ(ierr);
771   ctx = (PC_Telescope_DMDACtx*)sred->dm_ctx;
772   subcomm = PetscSubcommChild(sred->psubcomm);
773   ierr = MatNullSpaceGetVecs(nullspace,&has_const,&n,&vecs);CHKERRQ(ierr);
774 
775   if (isActiveRank(sred->psubcomm)) {
776     /* create new vectors */
777     if (n) {
778       ierr = VecDuplicateVecs(sred->xred,n,&sub_vecs);CHKERRQ(ierr);
779     }
780   }
781 
782   /* copy entries */
783   for (k=0; k<n; k++) {
784     const PetscScalar *x_array;
785     PetscScalar       *LA_sub_vec;
786     PetscInt          st,ed,bs;
787 
788     /* permute vector into ordering associated with re-partitioned dmda */
789     ierr = MatMultTranspose(ctx->permutation,vecs[k],ctx->xp);CHKERRQ(ierr);
790 
791     /* pull in vector x->xtmp */
792     ierr = VecScatterBegin(sred->scatter,ctx->xp,sred->xtmp,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
793     ierr = VecScatterEnd(sred->scatter,ctx->xp,sred->xtmp,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
794 
795     /* copy vector entires into xred */
796     ierr = VecGetBlockSize(sred->xtmp,&bs);CHKERRQ(ierr);
797     ierr = VecGetArrayRead(sred->xtmp,&x_array);CHKERRQ(ierr);
798     if (sub_vecs[k]) {
799       ierr = VecGetOwnershipRange(sub_vecs[k],&st,&ed);CHKERRQ(ierr);
800       ierr = VecGetArray(sub_vecs[k],&LA_sub_vec);CHKERRQ(ierr);
801       for (i=0; i<ed-st; i++) {
802         LA_sub_vec[i] = x_array[i];
803       }
804       ierr = VecRestoreArray(sub_vecs[k],&LA_sub_vec);CHKERRQ(ierr);
805     }
806     ierr = VecRestoreArrayRead(sred->xtmp,&x_array);CHKERRQ(ierr);
807   }
808 
809   if (isActiveRank(sred->psubcomm)) {
810     /* create new nullspace for redundant object */
811     ierr = MatNullSpaceCreate(subcomm,has_const,n,sub_vecs,&sub_nullspace);CHKERRQ(ierr);
812 
813     /* attach redundant nullspace to Bred */
814     ierr = MatSetNullSpace(sub_mat,sub_nullspace);CHKERRQ(ierr);
815     ierr = VecDestroyVecs(n,&sub_vecs);CHKERRQ(ierr);
816   }
817   PetscFunctionReturn(0);
818 }
819 
820 #undef __FUNCT__
821 #define __FUNCT__ "PCApply_Telescope_dmda"
822 PetscErrorCode PCApply_Telescope_dmda(PC pc,Vec x,Vec y)
823 {
824   PC_Telescope      sred = (PC_Telescope)pc->data;
825   PetscErrorCode    ierr;
826   Mat               perm;
827   Vec               xtmp,xp,xred,yred;
828   PetscInt          i,st,ed,bs;
829   VecScatter        scatter;
830   PetscScalar       *array;
831   const PetscScalar *x_array;
832   PC_Telescope_DMDACtx *ctx;
833 
834   ctx = (PC_Telescope_DMDACtx*)sred->dm_ctx;
835   xtmp    = sred->xtmp;
836   scatter = sred->scatter;
837   xred    = sred->xred;
838   yred    = sred->yred;
839   perm  = ctx->permutation;
840   xp    = ctx->xp;
841 
842   PetscFunctionBegin;
843   /* permute vector into ordering associated with re-partitioned dmda */
844   ierr = MatMultTranspose(perm,x,xp);CHKERRQ(ierr);
845 
846   /* pull in vector x->xtmp */
847   ierr = VecScatterBegin(scatter,xp,xtmp,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
848   ierr = VecScatterEnd(scatter,xp,xtmp,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
849 
850   /* copy vector entires into xred */
851   ierr = VecGetBlockSize(xtmp,&bs);CHKERRQ(ierr);
852   ierr = VecGetArrayRead(xtmp,&x_array);CHKERRQ(ierr);
853   if (xred) {
854     PetscScalar *LA_xred;
855     ierr = VecGetOwnershipRange(xred,&st,&ed);CHKERRQ(ierr);
856 
857     ierr = VecGetArray(xred,&LA_xred);CHKERRQ(ierr);
858     for (i=0; i<ed-st; i++) {
859       LA_xred[i] = x_array[i];
860     }
861     ierr = VecRestoreArray(xred,&LA_xred);CHKERRQ(ierr);
862   }
863   ierr = VecRestoreArrayRead(xtmp,&x_array);CHKERRQ(ierr);
864 
865   /* solve */
866   if (isActiveRank(sred->psubcomm)) {
867     ierr = KSPSolve(sred->ksp,xred,yred);CHKERRQ(ierr);
868   }
869 
870   /* return vector */
871   ierr = VecGetBlockSize(xtmp,&bs);CHKERRQ(ierr);
872   ierr = VecGetArray(xtmp,&array);CHKERRQ(ierr);
873   if (yred) {
874     const PetscScalar *LA_yred;
875     ierr = VecGetOwnershipRange(yred,&st,&ed);CHKERRQ(ierr);
876     ierr = VecGetArrayRead(yred,&LA_yred);CHKERRQ(ierr);
877     for (i=0; i<ed-st; i++) {
878       array[i] = LA_yred[i];
879     }
880     ierr = VecRestoreArrayRead(yred,&LA_yred);CHKERRQ(ierr);
881   }
882   ierr = VecRestoreArray(xtmp,&array);CHKERRQ(ierr);
883   ierr = VecScatterBegin(scatter,xtmp,xp,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
884   ierr = VecScatterEnd(scatter,xtmp,xp,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
885   ierr = MatMult(perm,xp,y);CHKERRQ(ierr);
886   PetscFunctionReturn(0);
887 }
888 
889 #undef __FUNCT__
890 #define __FUNCT__ "PCReset_Telescope_dmda"
891 PetscErrorCode PCReset_Telescope_dmda(PC pc)
892 {
893   PetscErrorCode       ierr;
894   PC_Telescope         sred = (PC_Telescope)pc->data;
895   PC_Telescope_DMDACtx *ctx;
896 
897   PetscFunctionBegin;
898   ctx = (PC_Telescope_DMDACtx*)sred->dm_ctx;
899   ierr = VecDestroy(&ctx->xp);CHKERRQ(ierr);
900   ierr = MatDestroy(&ctx->permutation);CHKERRQ(ierr);
901   ierr = DMDestroy(&ctx->dmrepart);CHKERRQ(ierr);
902   ierr = PetscFree(ctx->range_i_re);CHKERRQ(ierr);
903   ierr = PetscFree(ctx->range_j_re);CHKERRQ(ierr);
904   ierr = PetscFree(ctx->range_k_re);CHKERRQ(ierr);
905   ierr = PetscFree(ctx->start_i_re);CHKERRQ(ierr);
906   ierr = PetscFree(ctx->start_j_re);CHKERRQ(ierr);
907   ierr = PetscFree(ctx->start_k_re);CHKERRQ(ierr);
908   PetscFunctionReturn(0);
909 }
910 
911 #undef __FUNCT__
912 #define __FUNCT__ "DMView_DMDAShort_3d"
913 PetscErrorCode DMView_DMDAShort_3d(DM dm,PetscViewer v)
914 {
915   PetscInt       M,N,P,m,n,p,ndof,nsw;
916   MPI_Comm       comm;
917   PetscMPIInt    size;
918   const char*    prefix;
919   PetscErrorCode ierr;
920 
921   PetscFunctionBegin;
922   ierr = PetscObjectGetComm((PetscObject)dm,&comm);CHKERRQ(ierr);
923   ierr = MPI_Comm_size(comm,&size);CHKERRQ(ierr);
924   ierr = DMGetOptionsPrefix(dm,&prefix);CHKERRQ(ierr);
925   ierr = DMDAGetInfo(dm,NULL,&M,&N,&P,&m,&n,&p,&ndof,&nsw,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
926   if (prefix) {ierr = PetscViewerASCIIPrintf(v,"DMDA Object:    (%s)    %d MPI processes\n",prefix,size);CHKERRQ(ierr);}
927   else {ierr = PetscViewerASCIIPrintf(v,"DMDA Object:    %d MPI processes\n",size);CHKERRQ(ierr);}
928   ierr = PetscViewerASCIIPrintf(v,"  M %D N %D P %D m %D n %D p %D dof %D overlap %D\n",M,N,P,m,n,p,ndof,nsw);CHKERRQ(ierr);
929   PetscFunctionReturn(0);
930 }
931 
932 #undef __FUNCT__
933 #define __FUNCT__ "DMView_DMDAShort_2d"
934 PetscErrorCode DMView_DMDAShort_2d(DM dm,PetscViewer v)
935 {
936   PetscInt       M,N,m,n,ndof,nsw;
937   MPI_Comm       comm;
938   PetscMPIInt    size;
939   const char*    prefix;
940   PetscErrorCode ierr;
941 
942   PetscFunctionBegin;
943   ierr = PetscObjectGetComm((PetscObject)dm,&comm);CHKERRQ(ierr);
944   ierr = MPI_Comm_size(comm,&size);CHKERRQ(ierr);
945   ierr = DMGetOptionsPrefix(dm,&prefix);CHKERRQ(ierr);
946   ierr = DMDAGetInfo(dm,NULL,&M,&N,NULL,&m,&n,NULL,&ndof,&nsw,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
947   if (prefix) {PetscViewerASCIIPrintf(v,"DMDA Object:    (%s)    %d MPI processes\n",prefix,size);CHKERRQ(ierr);}
948   else {ierr = PetscViewerASCIIPrintf(v,"DMDA Object:    %d MPI processes\n",size);CHKERRQ(ierr);}
949   ierr = PetscViewerASCIIPrintf(v,"  M %D N %D m %D n %D dof %D overlap %D\n",M,N,m,n,ndof,nsw);CHKERRQ(ierr);
950   PetscFunctionReturn(0);
951 }
952 
953 #undef __FUNCT__
954 #define __FUNCT__ "DMView_DMDAShort"
955 PetscErrorCode DMView_DMDAShort(DM dm,PetscViewer v)
956 {
957   PetscErrorCode ierr;
958   PetscInt       dim;
959 
960   PetscFunctionBegin;
961   ierr = DMDAGetInfo(dm,&dim,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
962   switch (dim) {
963   case 2: ierr = DMView_DMDAShort_2d(dm,v);CHKERRQ(ierr);
964     break;
965   case 3: ierr = DMView_DMDAShort_3d(dm,v);CHKERRQ(ierr);
966     break;
967   }
968   PetscFunctionReturn(0);
969 }
970 
971