xref: /petsc/src/ksp/pc/impls/telescope/telescope_dmda.c (revision c2be2c73820c81ee05c25cc57db99e4a87e0b3dd)
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 
143     Ml = ni - si;
144     Nl = nj - sj;
145   } else {
146     Ml = Nl = 1;
147   }
148 
149   ierr = PetscMalloc1(Ml*Nl*2,&fine_indices);CHKERRQ(ierr);
150   c = 0;
151   if (isActiveRank(psubcomm)) {
152     for (j=sj; j<sj+nj; j++) {
153       for (i=si; i<si+ni; i++) {
154         nidx = (i) + (j)*M;
155         fine_indices[c  ] = 2 * nidx     ;
156         fine_indices[c+1] = 2 * nidx + 1 ;
157         c = c + 2;
158       }
159     }
160     if (c != Ml*Nl*2) SETERRQ3(PETSC_COMM_SELF,PETSC_ERR_PLIB,"c %D should equal 2 * Ml %D * Nl %D",c,Ml,Nl);
161   } else {
162     i = si;
163     j = sj;
164     nidx = (i) + (j)*M;
165     fine_indices[0] = 2 * nidx     ;
166     fine_indices[1] = 2 * nidx + 1 ;
167     if (2 != Ml*Nl*2) SETERRQ3(PETSC_COMM_SELF,PETSC_ERR_PLIB,"c %D should equal 2 * Ml %D * Nl %D",c,Ml,Nl);
168   }
169 
170   /* generate scatter */
171   ierr = ISCreateGeneral(PetscObjectComm((PetscObject)dm),Ml*Nl*2,fine_indices,PETSC_USE_POINTER,&is_fine);CHKERRQ(ierr);
172   ierr = ISCreateStride(PETSC_COMM_SELF,Ml*Nl*2,0,1,&is_local);CHKERRQ(ierr);
173 
174   /* scatter */
175   ierr = VecCreate(PETSC_COMM_SELF,&perm_coors);CHKERRQ(ierr);
176   ierr = VecSetSizes(perm_coors,PETSC_DECIDE,Ml*Nl*2);CHKERRQ(ierr);
177   ierr = VecSetType(perm_coors,VECSEQ);CHKERRQ(ierr);
178 
179   ierr = VecScatterCreate(coor_natural,is_fine,perm_coors,is_local,&sctx);CHKERRQ(ierr);
180   ierr = VecScatterBegin(sctx,coor_natural,perm_coors,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
181   ierr = VecScatterEnd(  sctx,coor_natural,perm_coors,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
182   /* access */
183   if (isActiveRank(psubcomm)) {
184     Vec               _coors;
185     const PetscScalar *LA_perm;
186     PetscScalar       *LA_coors;
187 
188     ierr = DMGetCoordinates(subdm,&_coors);CHKERRQ(ierr);
189     ierr = VecGetArrayRead(perm_coors,&LA_perm);CHKERRQ(ierr);
190     ierr = VecGetArray(_coors,&LA_coors);CHKERRQ(ierr);
191     for (i=0; i<Ml*Nl*2; i++) {
192       LA_coors[i] = LA_perm[i];
193     }
194     ierr = VecRestoreArray(_coors,&LA_coors);CHKERRQ(ierr);
195     ierr = VecRestoreArrayRead(perm_coors,&LA_perm);CHKERRQ(ierr);
196   }
197 
198   /* update local coords */
199   if (isActiveRank(psubcomm)) {
200     DM  _dmc;
201     Vec _coors,_coors_local;
202     ierr = DMGetCoordinateDM(subdm,&_dmc);CHKERRQ(ierr);
203     ierr = DMGetCoordinates(subdm,&_coors);CHKERRQ(ierr);
204     ierr = DMGetCoordinatesLocal(subdm,&_coors_local);CHKERRQ(ierr);
205     ierr = DMGlobalToLocalBegin(_dmc,_coors,INSERT_VALUES,_coors_local);CHKERRQ(ierr);
206     ierr = DMGlobalToLocalEnd(_dmc,_coors,INSERT_VALUES,_coors_local);CHKERRQ(ierr);
207   }
208   ierr = VecScatterDestroy(&sctx);CHKERRQ(ierr);
209   ierr = ISDestroy(&is_fine);CHKERRQ(ierr);
210   ierr = PetscFree(fine_indices);CHKERRQ(ierr);
211   ierr = ISDestroy(&is_local);CHKERRQ(ierr);
212   ierr = VecDestroy(&perm_coors);CHKERRQ(ierr);
213   ierr = VecDestroy(&coor_natural);CHKERRQ(ierr);
214   PetscFunctionReturn(0);
215 }
216 
217 #undef __FUNCT__
218 #define __FUNCT__ "PCTelescopeSetUp_dmda_repart_coors3d"
219 PetscErrorCode PCTelescopeSetUp_dmda_repart_coors3d(PetscSubcomm psubcomm,DM dm,DM subdm)
220 {
221   PetscErrorCode ierr;
222   DM             cdm;
223   Vec            coor,coor_natural,perm_coors;
224   PetscInt       i,j,k,si,sj,sk,ni,nj,nk,M,N,P,Ml,Nl,Pl,c,nidx;
225   PetscInt       *fine_indices;
226   IS             is_fine,is_local;
227   VecScatter     sctx;
228 
229   PetscFunctionBegin;
230   ierr = DMGetCoordinates(dm,&coor);CHKERRQ(ierr);
231   if (!coor) PetscFunctionReturn(0);
232 
233   if (isActiveRank(psubcomm)) {
234     ierr = DMDASetUniformCoordinates(subdm,0.0,1.0,0.0,1.0,0.0,1.0);CHKERRQ(ierr);
235   }
236 
237   /* Get the coordinate vector from the distributed array */
238   ierr = DMGetCoordinateDM(dm,&cdm);CHKERRQ(ierr);
239   ierr = DMDACreateNaturalVector(cdm,&coor_natural);CHKERRQ(ierr);
240   ierr = DMDAGlobalToNaturalBegin(cdm,coor,INSERT_VALUES,coor_natural);CHKERRQ(ierr);
241   ierr = DMDAGlobalToNaturalEnd(cdm,coor,INSERT_VALUES,coor_natural);CHKERRQ(ierr);
242 
243   /* get indices of the guys I want to grab */
244   ierr = DMDAGetInfo(dm,NULL,&M,&N,&P,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
245 
246   if (isActiveRank(psubcomm)) {
247     ierr = DMDAGetCorners(subdm,&si,&sj,&sk,&ni,&nj,&nk);CHKERRQ(ierr);
248 
249     Ml = ni;
250     Nl = nj;
251     Pl = nk;
252   } else {
253     Ml = Nl = Pl = 1;
254   }
255 
256   ierr = PetscMalloc1(Ml*Nl*Pl*3,&fine_indices);CHKERRQ(ierr);
257 
258   c = 0;
259   if (isActiveRank(psubcomm)) {
260     for (k=sk; k<sk+nk; k++) {
261       for (j=sj; j<sj+nj; j++) {
262         for (i=si; i<si+ni; i++) {
263           nidx = (i) + (j)*M + (k)*M*N;
264           fine_indices[c  ] = 3 * nidx     ;
265           fine_indices[c+1] = 3 * nidx + 1 ;
266           fine_indices[c+2] = 3 * nidx + 2 ;
267           c = c + 3;
268         }
269       }
270     }
271   } else {
272     i = si;
273     j = sj;
274     k = sk;
275     nidx = (i) + (j)*M + (k)*M*N;
276     fine_indices[0] = 3 * nidx     ;
277     fine_indices[1] = 3 * nidx + 1 ;
278     fine_indices[2] = 3 * nidx + 2 ;
279   }
280 
281   /* generate scatter */
282   ierr = ISCreateGeneral(PetscObjectComm((PetscObject)dm),Ml*Nl*Pl*3,fine_indices,PETSC_USE_POINTER,&is_fine);CHKERRQ(ierr);
283   ierr = ISCreateStride(PETSC_COMM_SELF,Ml*Nl*Pl*3,0,1,&is_local);CHKERRQ(ierr);
284 
285   /* scatter */
286   ierr = VecCreate(PETSC_COMM_SELF,&perm_coors);CHKERRQ(ierr);
287   ierr = VecSetSizes(perm_coors,PETSC_DECIDE,Ml*Nl*Pl*3);CHKERRQ(ierr);
288   ierr = VecSetType(perm_coors,VECSEQ);CHKERRQ(ierr);
289   ierr = VecScatterCreate(coor_natural,is_fine,perm_coors,is_local,&sctx);CHKERRQ(ierr);
290   ierr = VecScatterBegin(sctx,coor_natural,perm_coors,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
291   ierr = VecScatterEnd(  sctx,coor_natural,perm_coors,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
292 
293   /* access */
294   if (isActiveRank(psubcomm)) {
295     Vec               _coors;
296     const PetscScalar *LA_perm;
297     PetscScalar       *LA_coors;
298 
299     ierr = DMGetCoordinates(subdm,&_coors);CHKERRQ(ierr);
300     ierr = VecGetArrayRead(perm_coors,&LA_perm);CHKERRQ(ierr);
301     ierr = VecGetArray(_coors,&LA_coors);CHKERRQ(ierr);
302     for (i=0; i<Ml*Nl*Pl*3; i++) {
303       LA_coors[i] = LA_perm[i];
304     }
305     ierr = VecRestoreArray(_coors,&LA_coors);CHKERRQ(ierr);
306     ierr = VecRestoreArrayRead(perm_coors,&LA_perm);CHKERRQ(ierr);
307   }
308 
309   /* update local coords */
310   if (isActiveRank(psubcomm)) {
311     DM  _dmc;
312     Vec _coors,_coors_local;
313 
314     ierr = DMGetCoordinateDM(subdm,&_dmc);CHKERRQ(ierr);
315     ierr = DMGetCoordinates(subdm,&_coors);CHKERRQ(ierr);
316     ierr = DMGetCoordinatesLocal(subdm,&_coors_local);CHKERRQ(ierr);
317     ierr = DMGlobalToLocalBegin(_dmc,_coors,INSERT_VALUES,_coors_local);CHKERRQ(ierr);
318     ierr = DMGlobalToLocalEnd(_dmc,_coors,INSERT_VALUES,_coors_local);CHKERRQ(ierr);
319   }
320 
321   ierr = VecScatterDestroy(&sctx);CHKERRQ(ierr);
322   ierr = ISDestroy(&is_fine);CHKERRQ(ierr);
323   ierr = PetscFree(fine_indices);CHKERRQ(ierr);
324   ierr = ISDestroy(&is_local);CHKERRQ(ierr);
325   ierr = VecDestroy(&perm_coors);CHKERRQ(ierr);
326   ierr = VecDestroy(&coor_natural);CHKERRQ(ierr);
327   PetscFunctionReturn(0);
328 }
329 
330 #undef __FUNCT__
331 #define __FUNCT__ "PCTelescopeSetUp_dmda_repart_coors"
332 PetscErrorCode PCTelescopeSetUp_dmda_repart_coors(PC pc,PC_Telescope sred,PC_Telescope_DMDACtx *ctx)
333 {
334   PetscInt       dim;
335   DM             dm,subdm;
336   PetscSubcomm   psubcomm;
337   MPI_Comm       comm;
338   Vec            coor;
339   PetscErrorCode ierr;
340 
341   PetscFunctionBegin;
342   ierr = PCGetDM(pc,&dm);CHKERRQ(ierr);
343   ierr = DMGetCoordinates(dm,&coor);CHKERRQ(ierr);
344   if (!coor) PetscFunctionReturn(0);
345   psubcomm = sred->psubcomm;
346   comm = PetscSubcommParent(psubcomm);
347   subdm = ctx->dmrepart;
348 
349 
350   ierr = PetscInfo(pc,"PCTelescope: setting up the coordinates (DMDA)\n");CHKERRQ(ierr);
351   ierr = DMDAGetInfo(dm,&dim,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
352   switch (dim) {
353   case 1: SETERRQ(comm,PETSC_ERR_SUP,"Telescope: DMDA (1D) repartitioning not provided");
354     break;
355   case 2: PCTelescopeSetUp_dmda_repart_coors2d(psubcomm,dm,subdm);
356     break;
357   case 3: PCTelescopeSetUp_dmda_repart_coors3d(psubcomm,dm,subdm);
358     break;
359   }
360   PetscFunctionReturn(0);
361 }
362 
363 /* setup repartitioned dm */
364 #undef __FUNCT__
365 #define __FUNCT__ "PCTelescopeSetUp_dmda_repart"
366 PetscErrorCode PCTelescopeSetUp_dmda_repart(PC pc,PC_Telescope sred,PC_Telescope_DMDACtx *ctx)
367 {
368   PetscErrorCode  ierr;
369   DM              dm;
370   PetscInt        dim,nx,ny,nz,ndof,nsw,sum,k;
371   DMBoundaryType  bx,by,bz;
372   DMDAStencilType stencil;
373   const PetscInt  *_range_i_re;
374   const PetscInt  *_range_j_re;
375   const PetscInt  *_range_k_re;
376   DMDAInterpolationType itype;
377   PetscInt              refine_x,refine_y,refine_z;
378   MPI_Comm              comm,subcomm;
379   const char            *prefix;
380 
381   PetscFunctionBegin;
382   comm = PetscSubcommParent(sred->psubcomm);
383   subcomm = PetscSubcommChild(sred->psubcomm);
384   ierr = PCGetDM(pc,&dm);CHKERRQ(ierr);
385 
386   ierr = DMDAGetInfo(dm,&dim,&nx,&ny,&nz,NULL,NULL,NULL,&ndof,&nsw,&bx,&by,&bz,&stencil);CHKERRQ(ierr);
387   ierr = DMDAGetInterpolationType(dm,&itype);CHKERRQ(ierr);
388   ierr = DMDAGetRefinementFactor(dm,&refine_x,&refine_y,&refine_z);CHKERRQ(ierr);
389 
390   ctx->dmrepart = NULL;
391   _range_i_re = _range_j_re = _range_k_re = NULL;
392   /* Create DMDA on the child communicator */
393   if (isActiveRank(sred->psubcomm)) {
394     switch (dim) {
395     case 1:
396       ierr = PetscInfo(pc,"PCTelescope: setting up the DMDA on comm subset (1D)\n");CHKERRQ(ierr);
397       /*ierr = DMDACreate1d(subcomm,bx,nx,ndof,nsw,NULL,&ctx->dmrepart);CHKERRQ(ierr);*/
398       ny = nz = 1;
399       by = bz = DM_BOUNDARY_NONE;
400       break;
401     case 2:
402       ierr = PetscInfo(pc,"PCTelescope: setting up the DMDA on comm subset (2D)\n");CHKERRQ(ierr);
403       /*ierr = DMDACreate2d(subcomm,bx,by,stencil,nx,ny, PETSC_DECIDE,PETSC_DECIDE, ndof,nsw, NULL,NULL,&ctx->dmrepart);CHKERRQ(ierr);*/
404       nz = 1;
405       bz = DM_BOUNDARY_NONE;
406       break;
407     case 3:
408       ierr = PetscInfo(pc,"PCTelescope: setting up the DMDA on comm subset (3D)\n");CHKERRQ(ierr);
409       /*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);*/
410       break;
411     }
412     /*
413      The API DMDACreate1d(), DMDACreate2d(), DMDACreate3d() does not allow us to set/append
414      a unique option prefix for the DM, thus I prefer to expose the contents of these API's here.
415      This allows users to control the partitioning of the subDM.
416     */
417     ierr = DMDACreate(subcomm,&ctx->dmrepart);CHKERRQ(ierr);
418     /* Set unique option prefix name */
419     ierr = DMGetOptionsPrefix(dm,&prefix);CHKERRQ(ierr);
420     ierr = DMSetOptionsPrefix(ctx->dmrepart,prefix);CHKERRQ(ierr);
421     ierr = DMAppendOptionsPrefix(ctx->dmrepart,"repart_");CHKERRQ(ierr);
422     /* standard setup from DMDACreate{1,2,3}d() */
423     ierr = DMSetDimension(ctx->dmrepart,dim);CHKERRQ(ierr);
424     ierr = DMDASetSizes(ctx->dmrepart,nx,ny,nz);CHKERRQ(ierr);
425     ierr = DMDASetNumProcs(ctx->dmrepart,PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE);CHKERRQ(ierr);
426     ierr = DMDASetBoundaryType(ctx->dmrepart,bx,by,bz);CHKERRQ(ierr);
427     ierr = DMDASetDof(ctx->dmrepart,ndof);CHKERRQ(ierr);
428     ierr = DMDASetStencilType(ctx->dmrepart,stencil);CHKERRQ(ierr);
429     ierr = DMDASetStencilWidth(ctx->dmrepart,nsw);CHKERRQ(ierr);
430     ierr = DMDASetOwnershipRanges(ctx->dmrepart,NULL,NULL,NULL);CHKERRQ(ierr);
431     ierr = DMSetFromOptions(ctx->dmrepart);CHKERRQ(ierr);
432     ierr = DMSetUp(ctx->dmrepart);CHKERRQ(ierr);
433     /* Set refinement factors and interpolation type from the partent */
434     ierr = DMDASetRefinementFactor(ctx->dmrepart,refine_x,refine_y,refine_z);CHKERRQ(ierr);
435     ierr = DMDASetInterpolationType(ctx->dmrepart,itype);CHKERRQ(ierr);
436 
437     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);
438     ierr = DMDAGetOwnershipRanges(ctx->dmrepart,&_range_i_re,&_range_j_re,&_range_k_re);CHKERRQ(ierr);
439   }
440 
441   /* generate ranges for repartitioned dm */
442   /* note - assume rank 0 always participates */
443   ierr = MPI_Bcast(&ctx->Mp_re,1,MPIU_INT,0,comm);CHKERRQ(ierr);
444   ierr = MPI_Bcast(&ctx->Np_re,1,MPIU_INT,0,comm);CHKERRQ(ierr);
445   ierr = MPI_Bcast(&ctx->Pp_re,1,MPIU_INT,0,comm);CHKERRQ(ierr);
446 
447   ierr = PetscCalloc1(ctx->Mp_re,&ctx->range_i_re);CHKERRQ(ierr);
448   ierr = PetscCalloc1(ctx->Np_re,&ctx->range_j_re);CHKERRQ(ierr);
449   ierr = PetscCalloc1(ctx->Pp_re,&ctx->range_k_re);CHKERRQ(ierr);
450 
451   if (_range_i_re) {ierr = PetscMemcpy(ctx->range_i_re,_range_i_re,sizeof(PetscInt)*ctx->Mp_re);CHKERRQ(ierr);}
452   if (_range_j_re) {ierr = PetscMemcpy(ctx->range_j_re,_range_j_re,sizeof(PetscInt)*ctx->Np_re);CHKERRQ(ierr);}
453   if (_range_k_re) {ierr = PetscMemcpy(ctx->range_k_re,_range_k_re,sizeof(PetscInt)*ctx->Pp_re);CHKERRQ(ierr);}
454 
455   ierr = MPI_Bcast(ctx->range_i_re,ctx->Mp_re,MPIU_INT,0,comm);CHKERRQ(ierr);
456   ierr = MPI_Bcast(ctx->range_j_re,ctx->Np_re,MPIU_INT,0,comm);CHKERRQ(ierr);
457   ierr = MPI_Bcast(ctx->range_k_re,ctx->Pp_re,MPIU_INT,0,comm);CHKERRQ(ierr);
458 
459   ierr = PetscMalloc1(ctx->Mp_re,&ctx->start_i_re);CHKERRQ(ierr);
460   ierr = PetscMalloc1(ctx->Np_re,&ctx->start_j_re);CHKERRQ(ierr);
461   ierr = PetscMalloc1(ctx->Pp_re,&ctx->start_k_re);CHKERRQ(ierr);
462 
463   sum = 0;
464   for (k=0; k<ctx->Mp_re; k++) {
465     ctx->start_i_re[k] = sum;
466     sum += ctx->range_i_re[k];
467   }
468 
469   sum = 0;
470   for (k=0; k<ctx->Np_re; k++) {
471     ctx->start_j_re[k] = sum;
472     sum += ctx->range_j_re[k];
473   }
474 
475   sum = 0;
476   for (k=0; k<ctx->Pp_re; k++) {
477     ctx->start_k_re[k] = sum;
478     sum += ctx->range_k_re[k];
479   }
480 
481   /* attach dm to ksp on sub communicator */
482   if (isActiveRank(sred->psubcomm)) {
483     ierr = KSPSetDM(sred->ksp,ctx->dmrepart);CHKERRQ(ierr);
484     ierr = KSPSetDMActive(sred->ksp,PETSC_FALSE);CHKERRQ(ierr);
485   }
486   PetscFunctionReturn(0);
487 }
488 
489 #undef __FUNCT__
490 #define __FUNCT__ "PCTelescopeSetUp_dmda_permutation_3d"
491 PetscErrorCode PCTelescopeSetUp_dmda_permutation_3d(PC pc,PC_Telescope sred,PC_Telescope_DMDACtx *ctx)
492 {
493   PetscErrorCode ierr;
494   DM             dm;
495   MPI_Comm       comm;
496   Mat            Pscalar,P;
497   PetscInt       ndof;
498   PetscInt       i,j,k,location,startI[3],endI[3],lenI[3],nx,ny,nz;
499   PetscInt       sr,er,Mr;
500   Vec            V;
501 
502   PetscFunctionBegin;
503   ierr = PetscInfo(pc,"PCTelescope: setting up the permutation matrix (DMDA-3D)\n");CHKERRQ(ierr);
504   ierr = PetscObjectGetComm((PetscObject)pc,&comm);CHKERRQ(ierr);
505 
506   ierr = PCGetDM(pc,&dm);CHKERRQ(ierr);
507   ierr = DMDAGetInfo(dm,NULL,&nx,&ny,&nz,NULL,NULL,NULL,&ndof,NULL,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
508 
509   ierr = DMGetGlobalVector(dm,&V);CHKERRQ(ierr);
510   ierr = VecGetSize(V,&Mr);CHKERRQ(ierr);
511   ierr = VecGetOwnershipRange(V,&sr,&er);CHKERRQ(ierr);
512   ierr = DMRestoreGlobalVector(dm,&V);CHKERRQ(ierr);
513   sr = sr / ndof;
514   er = er / ndof;
515   Mr = Mr / ndof;
516 
517   ierr = MatCreate(comm,&Pscalar);CHKERRQ(ierr);
518   ierr = MatSetSizes(Pscalar,(er-sr),(er-sr),Mr,Mr);CHKERRQ(ierr);
519   ierr = MatSetType(Pscalar,MATAIJ);CHKERRQ(ierr);
520   ierr = MatSeqAIJSetPreallocation(Pscalar,2,NULL);CHKERRQ(ierr);
521   ierr = MatMPIAIJSetPreallocation(Pscalar,2,NULL,2,NULL);CHKERRQ(ierr);
522 
523   ierr = DMDAGetCorners(dm,NULL,NULL,NULL,&lenI[0],&lenI[1],&lenI[2]);CHKERRQ(ierr);
524   ierr = DMDAGetCorners(dm,&startI[0],&startI[1],&startI[2],&endI[0],&endI[1],&endI[2]);CHKERRQ(ierr);
525   endI[0] += startI[0];
526   endI[1] += startI[1];
527   endI[2] += startI[2];
528 
529   for (k=startI[2]; k<endI[2]; k++) {
530     for (j=startI[1]; j<endI[1]; j++) {
531       for (i=startI[0]; i<endI[0]; i++) {
532         PetscMPIInt rank_ijk_re,rank_reI[3];
533         PetscInt    s0_re;
534         PetscInt    ii,jj,kk,local_ijk_re,mapped_ijk;
535         PetscInt    lenI_re[3];
536 
537         location = (i - startI[0]) + (j - startI[1])*lenI[0] + (k - startI[2])*lenI[0]*lenI[1];
538         ierr = _DMDADetermineRankFromGlobalIJK(3,i,j,k,   ctx->Mp_re,ctx->Np_re,ctx->Pp_re,
539                                                ctx->start_i_re,ctx->start_j_re,ctx->start_k_re,
540                                                ctx->range_i_re,ctx->range_j_re,ctx->range_k_re,
541                                                &rank_reI[0],&rank_reI[1],&rank_reI[2],&rank_ijk_re);CHKERRQ(ierr);
542         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);
543         ii = i - ctx->start_i_re[ rank_reI[0] ];
544         if (ii < 0) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"[dmdarepart-perm3d] index error ii");
545         jj = j - ctx->start_j_re[ rank_reI[1] ];
546         if (jj < 0) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"[dmdarepart-perm3d] index error jj");
547         kk = k - ctx->start_k_re[ rank_reI[2] ];
548         if (kk < 0) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"[dmdarepart-perm3d] index error kk");
549         lenI_re[0] = ctx->range_i_re[ rank_reI[0] ];
550         lenI_re[1] = ctx->range_j_re[ rank_reI[1] ];
551         lenI_re[2] = ctx->range_k_re[ rank_reI[2] ];
552         local_ijk_re = ii + jj * lenI_re[0] + kk * lenI_re[0] * lenI_re[1];
553         mapped_ijk = s0_re + local_ijk_re;
554         ierr = MatSetValue(Pscalar,sr+location,mapped_ijk,1.0,INSERT_VALUES);CHKERRQ(ierr);
555       }
556     }
557   }
558   ierr = MatAssemblyBegin(Pscalar,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
559   ierr = MatAssemblyEnd(Pscalar,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
560   ierr = MatCreateMAIJ(Pscalar,ndof,&P);CHKERRQ(ierr);
561   ierr = MatDestroy(&Pscalar);CHKERRQ(ierr);
562   ctx->permutation = P;
563   PetscFunctionReturn(0);
564 }
565 
566 #undef __FUNCT__
567 #define __FUNCT__ "PCTelescopeSetUp_dmda_permutation_2d"
568 PetscErrorCode PCTelescopeSetUp_dmda_permutation_2d(PC pc,PC_Telescope sred,PC_Telescope_DMDACtx *ctx)
569 {
570   PetscErrorCode ierr;
571   DM             dm;
572   MPI_Comm       comm;
573   Mat            Pscalar,P;
574   PetscInt       ndof;
575   PetscInt       i,j,location,startI[2],endI[2],lenI[2],nx,ny,nz;
576   PetscInt       sr,er,Mr;
577   Vec            V;
578 
579   PetscFunctionBegin;
580   ierr = PetscInfo(pc,"PCTelescope: setting up the permutation matrix (DMDA-2D)\n");CHKERRQ(ierr);
581   ierr = PetscObjectGetComm((PetscObject)pc,&comm);CHKERRQ(ierr);
582   ierr = PCGetDM(pc,&dm);CHKERRQ(ierr);
583   ierr = DMDAGetInfo(dm,NULL,&nx,&ny,&nz,NULL,NULL,NULL,&ndof,NULL,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
584   ierr = DMGetGlobalVector(dm,&V);CHKERRQ(ierr);
585   ierr = VecGetSize(V,&Mr);CHKERRQ(ierr);
586   ierr = VecGetOwnershipRange(V,&sr,&er);CHKERRQ(ierr);
587   ierr = DMRestoreGlobalVector(dm,&V);CHKERRQ(ierr);
588   sr = sr / ndof;
589   er = er / ndof;
590   Mr = Mr / ndof;
591 
592   ierr = MatCreate(comm,&Pscalar);CHKERRQ(ierr);
593   ierr = MatSetSizes(Pscalar,(er-sr),(er-sr),Mr,Mr);CHKERRQ(ierr);
594   ierr = MatSetType(Pscalar,MATAIJ);CHKERRQ(ierr);
595   ierr = MatSeqAIJSetPreallocation(Pscalar,2,NULL);CHKERRQ(ierr);
596   ierr = MatMPIAIJSetPreallocation(Pscalar,2,NULL,2,NULL);CHKERRQ(ierr);
597 
598   ierr = DMDAGetCorners(dm,NULL,NULL,NULL,&lenI[0],&lenI[1],NULL);CHKERRQ(ierr);
599   ierr = DMDAGetCorners(dm,&startI[0],&startI[1],NULL,&endI[0],&endI[1],NULL);CHKERRQ(ierr);
600   endI[0] += startI[0];
601   endI[1] += startI[1];
602 
603   for (j=startI[1]; j<endI[1]; j++) {
604     for (i=startI[0]; i<endI[0]; i++) {
605       PetscMPIInt rank_ijk_re,rank_reI[3];
606       PetscInt    s0_re;
607       PetscInt    ii,jj,local_ijk_re,mapped_ijk;
608       PetscInt    lenI_re[3];
609 
610       location = (i - startI[0]) + (j - startI[1])*lenI[0];
611       ierr = _DMDADetermineRankFromGlobalIJK(2,i,j,0,   ctx->Mp_re,ctx->Np_re,ctx->Pp_re,
612                                              ctx->start_i_re,ctx->start_j_re,ctx->start_k_re,
613                                              ctx->range_i_re,ctx->range_j_re,ctx->range_k_re,
614                                              &rank_reI[0],&rank_reI[1],NULL,&rank_ijk_re);CHKERRQ(ierr);
615 
616       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);
617 
618       ii = i - ctx->start_i_re[ rank_reI[0] ];
619       if (ii < 0) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"[dmdarepart-perm2d] index error ii");
620       jj = j - ctx->start_j_re[ rank_reI[1] ];
621       if (jj < 0) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"[dmdarepart-perm2d] index error jj");
622 
623       lenI_re[0] = ctx->range_i_re[ rank_reI[0] ];
624       lenI_re[1] = ctx->range_j_re[ rank_reI[1] ];
625       local_ijk_re = ii + jj * lenI_re[0];
626       mapped_ijk = s0_re + local_ijk_re;
627       ierr = MatSetValue(Pscalar,sr+location,mapped_ijk,1.0,INSERT_VALUES);CHKERRQ(ierr);
628     }
629   }
630   ierr = MatAssemblyBegin(Pscalar,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
631   ierr = MatAssemblyEnd(Pscalar,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
632   ierr = MatCreateMAIJ(Pscalar,ndof,&P);CHKERRQ(ierr);
633   ierr = MatDestroy(&Pscalar);CHKERRQ(ierr);
634   ctx->permutation = P;
635   PetscFunctionReturn(0);
636 }
637 
638 #undef __FUNCT__
639 #define __FUNCT__ "PCTelescopeSetUp_dmda_scatters"
640 PetscErrorCode PCTelescopeSetUp_dmda_scatters(PC pc,PC_Telescope sred,PC_Telescope_DMDACtx *ctx)
641 {
642   PetscErrorCode ierr;
643   Vec            xred,yred,xtmp,x,xp;
644   VecScatter     scatter;
645   IS             isin;
646   Mat            B;
647   PetscInt       m,bs,st,ed;
648   MPI_Comm       comm;
649 
650   PetscFunctionBegin;
651   ierr = PetscObjectGetComm((PetscObject)pc,&comm);CHKERRQ(ierr);
652   ierr = PCGetOperators(pc,NULL,&B);CHKERRQ(ierr);
653   ierr = MatCreateVecs(B,&x,NULL);CHKERRQ(ierr);
654   ierr = MatGetBlockSize(B,&bs);CHKERRQ(ierr);
655   ierr = VecDuplicate(x,&xp);CHKERRQ(ierr);
656   m = bs;
657   xred = NULL;
658   yred = NULL;
659   if (isActiveRank(sred->psubcomm)) {
660     ierr = DMCreateGlobalVector(ctx->dmrepart,&xred);CHKERRQ(ierr);
661     ierr = VecDuplicate(xred,&yred);CHKERRQ(ierr);
662     ierr = VecGetOwnershipRange(xred,&st,&ed);CHKERRQ(ierr);
663     ierr = ISCreateStride(comm,ed-st,st,1,&isin);CHKERRQ(ierr);
664     ierr = VecGetLocalSize(xred,&m);
665   } else {
666     /* fetch some local owned data - just to deal with avoiding zero length ownership on range */
667     ierr = VecGetOwnershipRange(x,&st,&ed);CHKERRQ(ierr);
668     ierr = ISCreateStride(comm,bs,st,1,&isin);CHKERRQ(ierr);
669   }
670   ierr = ISSetBlockSize(isin,bs);CHKERRQ(ierr);
671   ierr = VecCreate(comm,&xtmp);CHKERRQ(ierr);
672   ierr = VecSetSizes(xtmp,m,PETSC_DECIDE);CHKERRQ(ierr);
673   ierr = VecSetBlockSize(xtmp,bs);CHKERRQ(ierr);
674   ierr = VecSetType(xtmp,((PetscObject)x)->type_name);CHKERRQ(ierr);
675   ierr = VecScatterCreate(x,isin,xtmp,NULL,&scatter);CHKERRQ(ierr);
676   sred->xred    = xred;
677   sred->yred    = yred;
678   sred->isin    = isin;
679   sred->scatter = scatter;
680   sred->xtmp    = xtmp;
681 
682   ctx->xp       = xp;
683   ierr = VecDestroy(&x);CHKERRQ(ierr);
684   PetscFunctionReturn(0);
685 }
686 
687 #undef __FUNCT__
688 #define __FUNCT__ "PCTelescopeSetUp_dmda"
689 PetscErrorCode PCTelescopeSetUp_dmda(PC pc,PC_Telescope sred)
690 {
691   PC_Telescope_DMDACtx *ctx;
692   PetscInt                 dim;
693   DM                       dm;
694   MPI_Comm                 comm;
695   PetscErrorCode           ierr;
696 
697   PetscFunctionBegin;
698   ierr = PetscInfo(pc,"PCTelescope: setup (DMDA)\n");CHKERRQ(ierr);
699   PetscMalloc1(1,&ctx);
700   PetscMemzero(ctx,sizeof(PC_Telescope_DMDACtx));
701   sred->dm_ctx = (void*)ctx;
702 
703   ierr = PetscObjectGetComm((PetscObject)pc,&comm);CHKERRQ(ierr);
704   ierr = PCGetDM(pc,&dm);CHKERRQ(ierr);
705   ierr = DMDAGetInfo(dm,&dim,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
706 
707   PCTelescopeSetUp_dmda_repart(pc,sred,ctx);
708   PCTelescopeSetUp_dmda_repart_coors(pc,sred,ctx);
709   switch (dim) {
710   case 1: SETERRQ(comm,PETSC_ERR_SUP,"Telescope: DMDA (1D) repartitioning not provided");
711     break;
712   case 2: ierr = PCTelescopeSetUp_dmda_permutation_2d(pc,sred,ctx);CHKERRQ(ierr);
713     break;
714   case 3: ierr = PCTelescopeSetUp_dmda_permutation_3d(pc,sred,ctx);CHKERRQ(ierr);
715     break;
716   }
717   ierr = PCTelescopeSetUp_dmda_scatters(pc,sred,ctx);CHKERRQ(ierr);
718   PetscFunctionReturn(0);
719 }
720 
721 #undef __FUNCT__
722 #define __FUNCT__ "PCTelescopeMatCreate_dmda"
723 PetscErrorCode PCTelescopeMatCreate_dmda(PC pc,PC_Telescope sred,MatReuse reuse,Mat *A)
724 {
725   PetscErrorCode ierr;
726   PC_Telescope_DMDACtx *ctx;
727   MPI_Comm       comm,subcomm;
728   Mat            Bperm,Bred,B,P;
729   PetscInt       nr,nc;
730   IS             isrow,iscol;
731   Mat            Blocal,*_Blocal;
732 
733   PetscFunctionBegin;
734   ierr = PetscInfo(pc,"PCTelescope: updating the redundant preconditioned operator (DMDA)\n");CHKERRQ(ierr);
735   ierr = PetscObjectGetComm((PetscObject)pc,&comm);CHKERRQ(ierr);
736     subcomm = PetscSubcommChild(sred->psubcomm);
737   ctx = (PC_Telescope_DMDACtx*)sred->dm_ctx;
738 
739   ierr = PCGetOperators(pc,NULL,&B);CHKERRQ(ierr);
740   ierr = MatGetSize(B,&nr,&nc);CHKERRQ(ierr);
741 
742   P = ctx->permutation;
743   ierr = MatPtAP(B,P,MAT_INITIAL_MATRIX,1.1,&Bperm);CHKERRQ(ierr);
744 
745   /* Get submatrices */
746   isrow = sred->isin;
747   ierr = ISCreateStride(comm,nc,0,1,&iscol);CHKERRQ(ierr);
748 
749   ierr = MatGetSubMatrices(Bperm,1,&isrow,&iscol,MAT_INITIAL_MATRIX,&_Blocal);CHKERRQ(ierr);
750   Blocal = *_Blocal;
751   Bred = NULL;
752   if (isActiveRank(sred->psubcomm)) {
753     PetscInt mm;
754 
755     if (reuse != MAT_INITIAL_MATRIX) {Bred = *A;}
756     ierr = MatGetSize(Blocal,&mm,NULL);CHKERRQ(ierr);
757     /* ierr = MatCreateMPIMatConcatenateSeqMat(subcomm,Blocal,PETSC_DECIDE,reuse,&Bred);CHKERRQ(ierr); */
758     ierr = MatCreateMPIMatConcatenateSeqMat(subcomm,Blocal,mm,reuse,&Bred);CHKERRQ(ierr);
759   }
760   *A = Bred;
761 
762   ierr = ISDestroy(&iscol);CHKERRQ(ierr);
763   ierr = MatDestroy(&Bperm);CHKERRQ(ierr);
764   ierr = MatDestroyMatrices(1,&_Blocal);CHKERRQ(ierr);
765   PetscFunctionReturn(0);
766 }
767 
768 #undef __FUNCT__
769 #define __FUNCT__ "PCTelescopeMatNullSpaceCreate_dmda"
770 PetscErrorCode PCTelescopeMatNullSpaceCreate_dmda(PC pc,PC_Telescope sred,Mat sub_mat)
771 {
772   PetscErrorCode   ierr;
773   MatNullSpace     nullspace,sub_nullspace;
774   Mat              A,B;
775   PetscBool        has_const;
776   PetscInt         i,k,n;
777   const Vec        *vecs;
778   Vec              *sub_vecs;
779   MPI_Comm         subcomm;
780   PC_Telescope_DMDACtx *ctx;
781 
782   PetscFunctionBegin;
783   ierr = PCGetOperators(pc,&A,&B);CHKERRQ(ierr);
784   ierr = MatGetNullSpace(B,&nullspace);CHKERRQ(ierr);
785   if (!nullspace) return(0);
786 
787   ierr = PetscInfo(pc,"PCTelescope: generating nullspace (DMDA)\n");CHKERRQ(ierr);
788   ctx = (PC_Telescope_DMDACtx*)sred->dm_ctx;
789   subcomm = PetscSubcommChild(sred->psubcomm);
790   ierr = MatNullSpaceGetVecs(nullspace,&has_const,&n,&vecs);CHKERRQ(ierr);
791 
792   if (isActiveRank(sred->psubcomm)) {
793     /* create new vectors */
794     if (n) {
795       ierr = VecDuplicateVecs(sred->xred,n,&sub_vecs);CHKERRQ(ierr);
796     }
797   }
798 
799   /* copy entries */
800   for (k=0; k<n; k++) {
801     const PetscScalar *x_array;
802     PetscScalar       *LA_sub_vec;
803     PetscInt          st,ed,bs;
804 
805     /* permute vector into ordering associated with re-partitioned dmda */
806     ierr = MatMultTranspose(ctx->permutation,vecs[k],ctx->xp);CHKERRQ(ierr);
807 
808     /* pull in vector x->xtmp */
809     ierr = VecScatterBegin(sred->scatter,ctx->xp,sred->xtmp,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
810     ierr = VecScatterEnd(sred->scatter,ctx->xp,sred->xtmp,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
811 
812     /* copy vector entires into xred */
813     ierr = VecGetBlockSize(sred->xtmp,&bs);CHKERRQ(ierr);
814     ierr = VecGetArrayRead(sred->xtmp,&x_array);CHKERRQ(ierr);
815     if (sub_vecs[k]) {
816       ierr = VecGetOwnershipRange(sub_vecs[k],&st,&ed);CHKERRQ(ierr);
817       ierr = VecGetArray(sub_vecs[k],&LA_sub_vec);CHKERRQ(ierr);
818       for (i=0; i<ed-st; i++) {
819         LA_sub_vec[i] = x_array[i];
820       }
821       ierr = VecRestoreArray(sub_vecs[k],&LA_sub_vec);CHKERRQ(ierr);
822     }
823     ierr = VecRestoreArrayRead(sred->xtmp,&x_array);CHKERRQ(ierr);
824   }
825 
826   if (isActiveRank(sred->psubcomm)) {
827     /* create new nullspace for redundant object */
828     ierr = MatNullSpaceCreate(subcomm,has_const,n,sub_vecs,&sub_nullspace);CHKERRQ(ierr);
829 
830     /* attach redundant nullspace to Bred */
831     ierr = MatSetNullSpace(sub_mat,sub_nullspace);CHKERRQ(ierr);
832     ierr = VecDestroyVecs(n,&sub_vecs);CHKERRQ(ierr);
833   }
834   PetscFunctionReturn(0);
835 }
836 
837 #undef __FUNCT__
838 #define __FUNCT__ "PCApply_Telescope_dmda"
839 PetscErrorCode PCApply_Telescope_dmda(PC pc,Vec x,Vec y)
840 {
841   PC_Telescope      sred = (PC_Telescope)pc->data;
842   PetscErrorCode    ierr;
843   Mat               perm;
844   Vec               xtmp,xp,xred,yred;
845   PetscInt          i,st,ed,bs;
846   VecScatter        scatter;
847   PetscScalar       *array;
848   const PetscScalar *x_array;
849   PC_Telescope_DMDACtx *ctx;
850 
851   ctx = (PC_Telescope_DMDACtx*)sred->dm_ctx;
852   xtmp    = sred->xtmp;
853   scatter = sred->scatter;
854   xred    = sred->xred;
855   yred    = sred->yred;
856   perm  = ctx->permutation;
857   xp    = ctx->xp;
858 
859   PetscFunctionBegin;
860   /* permute vector into ordering associated with re-partitioned dmda */
861   ierr = MatMultTranspose(perm,x,xp);CHKERRQ(ierr);
862 
863   /* pull in vector x->xtmp */
864   ierr = VecScatterBegin(scatter,xp,xtmp,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
865   ierr = VecScatterEnd(scatter,xp,xtmp,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
866 
867   /* copy vector entires into xred */
868   ierr = VecGetBlockSize(xtmp,&bs);CHKERRQ(ierr);
869   ierr = VecGetArrayRead(xtmp,&x_array);CHKERRQ(ierr);
870   if (xred) {
871     PetscScalar *LA_xred;
872     ierr = VecGetOwnershipRange(xred,&st,&ed);CHKERRQ(ierr);
873 
874     ierr = VecGetArray(xred,&LA_xred);CHKERRQ(ierr);
875     for (i=0; i<ed-st; i++) {
876       LA_xred[i] = x_array[i];
877     }
878     ierr = VecRestoreArray(xred,&LA_xred);CHKERRQ(ierr);
879   }
880   ierr = VecRestoreArrayRead(xtmp,&x_array);CHKERRQ(ierr);
881 
882   /* solve */
883   if (isActiveRank(sred->psubcomm)) {
884     ierr = KSPSolve(sred->ksp,xred,yred);CHKERRQ(ierr);
885   }
886 
887   /* return vector */
888   ierr = VecGetBlockSize(xtmp,&bs);CHKERRQ(ierr);
889   ierr = VecGetArray(xtmp,&array);CHKERRQ(ierr);
890   if (yred) {
891     const PetscScalar *LA_yred;
892     ierr = VecGetOwnershipRange(yred,&st,&ed);CHKERRQ(ierr);
893     ierr = VecGetArrayRead(yred,&LA_yred);CHKERRQ(ierr);
894     for (i=0; i<ed-st; i++) {
895       array[i] = LA_yred[i];
896     }
897     ierr = VecRestoreArrayRead(yred,&LA_yred);CHKERRQ(ierr);
898   } else {
899     for (i=0; i<bs; i++) {
900       array[i] = 0.0;
901     }
902   }
903   ierr = VecRestoreArray(xtmp,&array);CHKERRQ(ierr);
904   ierr = VecScatterBegin(scatter,xtmp,xp,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
905   ierr = VecScatterEnd(scatter,xtmp,xp,INSERT_VALUES,SCATTER_REVERSE);CHKERRQ(ierr);
906   ierr = MatMult(perm,xp,y);CHKERRQ(ierr);
907   PetscFunctionReturn(0);
908 }
909 
910 #undef __FUNCT__
911 #define __FUNCT__ "PCReset_Telescope_dmda"
912 PetscErrorCode PCReset_Telescope_dmda(PC pc)
913 {
914   PetscErrorCode       ierr;
915   PC_Telescope         sred = (PC_Telescope)pc->data;
916   PC_Telescope_DMDACtx *ctx;
917 
918   PetscFunctionBegin;
919   ctx = (PC_Telescope_DMDACtx*)sred->dm_ctx;
920   ierr = VecDestroy(&ctx->xp);CHKERRQ(ierr);
921   ierr = MatDestroy(&ctx->permutation);CHKERRQ(ierr);
922   ierr = DMDestroy(&ctx->dmrepart);CHKERRQ(ierr);
923   ierr = PetscFree(ctx->range_i_re);CHKERRQ(ierr);
924   ierr = PetscFree(ctx->range_j_re);CHKERRQ(ierr);
925   ierr = PetscFree(ctx->range_k_re);CHKERRQ(ierr);
926   ierr = PetscFree(ctx->start_i_re);CHKERRQ(ierr);
927   ierr = PetscFree(ctx->start_j_re);CHKERRQ(ierr);
928   ierr = PetscFree(ctx->start_k_re);CHKERRQ(ierr);
929   PetscFunctionReturn(0);
930 }
931 
932 #undef __FUNCT__
933 #define __FUNCT__ "DMView_DMDAShort_3d"
934 PetscErrorCode DMView_DMDAShort_3d(DM dm,PetscViewer v)
935 {
936   PetscInt       M,N,P,m,n,p,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,&P,&m,&n,&p,&ndof,&nsw,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
947   if (prefix) {ierr = 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 P %D m %D n %D p %D dof %D overlap %D\n",M,N,P,m,n,p,ndof,nsw);CHKERRQ(ierr);
950   PetscFunctionReturn(0);
951 }
952 
953 #undef __FUNCT__
954 #define __FUNCT__ "DMView_DMDAShort_2d"
955 PetscErrorCode DMView_DMDAShort_2d(DM dm,PetscViewer v)
956 {
957   PetscInt       M,N,m,n,ndof,nsw;
958   MPI_Comm       comm;
959   PetscMPIInt    size;
960   const char*    prefix;
961   PetscErrorCode ierr;
962 
963   PetscFunctionBegin;
964   ierr = PetscObjectGetComm((PetscObject)dm,&comm);CHKERRQ(ierr);
965   ierr = MPI_Comm_size(comm,&size);CHKERRQ(ierr);
966   ierr = DMGetOptionsPrefix(dm,&prefix);CHKERRQ(ierr);
967   ierr = DMDAGetInfo(dm,NULL,&M,&N,NULL,&m,&n,NULL,&ndof,&nsw,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
968   if (prefix) {PetscViewerASCIIPrintf(v,"DMDA Object:    (%s)    %d MPI processes\n",prefix,size);CHKERRQ(ierr);}
969   else {ierr = PetscViewerASCIIPrintf(v,"DMDA Object:    %d MPI processes\n",size);CHKERRQ(ierr);}
970   ierr = PetscViewerASCIIPrintf(v,"  M %D N %D m %D n %D dof %D overlap %D\n",M,N,m,n,ndof,nsw);CHKERRQ(ierr);
971   PetscFunctionReturn(0);
972 }
973 
974 #undef __FUNCT__
975 #define __FUNCT__ "DMView_DMDAShort"
976 PetscErrorCode DMView_DMDAShort(DM dm,PetscViewer v)
977 {
978   PetscErrorCode ierr;
979   PetscInt       dim;
980 
981   PetscFunctionBegin;
982   ierr = DMDAGetInfo(dm,&dim,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
983   switch (dim) {
984   case 2: ierr = DMView_DMDAShort_2d(dm,v);CHKERRQ(ierr);
985     break;
986   case 3: ierr = DMView_DMDAShort_3d(dm,v);CHKERRQ(ierr);
987     break;
988   }
989   PetscFunctionReturn(0);
990 }
991 
992