xref: /petsc/src/dm/impls/da/dasub.c (revision dfd676b1a855b7f967ece75a22ee7f6626d10f89)
1 
2 /*
3   Code for manipulating distributed regular arrays in parallel.
4 */
5 
6 #include <petsc/private/dmdaimpl.h>    /*I   "petscdmda.h"   I*/
7 
8 /*@
9    DMDAGetLogicalCoordinate - Returns a the i,j,k logical coordinate for the closest mesh point to a x,y,z point in the coordinates of the DMDA
10 
11    Collective on da
12 
13    Input Parameters:
14 +  da - the distributed array
15 .  x  - the first physical coordinate
16 .  y  - the second physical coordinate
17 -  z  - the third physical coordinate
18 
19    Output Parameters:
20 +  II - the first logical coordinate (-1 on processes that do not contain that point)
21 .  JJ - the second logical coordinate (-1 on processes that do not contain that point)
22 .  KK - the third logical coordinate (-1 on processes that do not contain that point)
23 .  X  - (optional) the first coordinate of the located grid point
24 .  Y  - (optional) the second coordinate of the located grid point
25 -  Z  - (optional) the third coordinate of the located grid point
26 
27    Level: advanced
28 
29    Notes:
30    All processors that share the DMDA must call this with the same coordinate value
31 
32 @*/
33 PetscErrorCode  DMDAGetLogicalCoordinate(DM da,PetscScalar x,PetscScalar y,PetscScalar z,PetscInt *II,PetscInt *JJ,PetscInt *KK,PetscScalar *X,PetscScalar *Y,PetscScalar *Z)
34 {
35   Vec            coors;
36   DM             dacoors;
37   DMDACoor2d     **c;
38   PetscInt       i,j,xs,xm,ys,ym;
39   PetscReal      d,D = PETSC_MAX_REAL,Dv;
40   PetscMPIInt    rank,root;
41 
42   PetscFunctionBegin;
43   PetscCheck(da->dim != 1,PetscObjectComm((PetscObject)da),PETSC_ERR_SUP,"Cannot get point from 1d DMDA");
44   PetscCheck(da->dim != 3,PetscObjectComm((PetscObject)da),PETSC_ERR_SUP,"Cannot get point from 3d DMDA");
45 
46   *II = -1;
47   *JJ = -1;
48 
49   PetscCall(DMGetCoordinateDM(da,&dacoors));
50   PetscCall(DMDAGetCorners(dacoors,&xs,&ys,NULL,&xm,&ym,NULL));
51   PetscCall(DMGetCoordinates(da,&coors));
52   PetscCall(DMDAVecGetArrayRead(dacoors,coors,&c));
53   for (j=ys; j<ys+ym; j++) {
54     for (i=xs; i<xs+xm; i++) {
55       d = PetscSqrtReal(PetscRealPart((c[j][i].x - x)*(c[j][i].x - x) + (c[j][i].y - y)*(c[j][i].y - y)));
56       if (d < D) {
57         D   = d;
58         *II = i;
59         *JJ = j;
60       }
61     }
62   }
63   PetscCall(MPIU_Allreduce(&D,&Dv,1,MPIU_REAL,MPIU_MIN,PetscObjectComm((PetscObject)da)));
64   if (D != Dv) {
65     *II  = -1;
66     *JJ  = -1;
67     rank = 0;
68   } else {
69     *X = c[*JJ][*II].x;
70     *Y = c[*JJ][*II].y;
71     PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)da),&rank));
72     rank++;
73   }
74   PetscCall(MPIU_Allreduce(&rank,&root,1,MPI_INT,MPI_SUM,PetscObjectComm((PetscObject)da)));
75   root--;
76   PetscCallMPI(MPI_Bcast(X,1,MPIU_SCALAR,root,PetscObjectComm((PetscObject)da)));
77   PetscCallMPI(MPI_Bcast(Y,1,MPIU_SCALAR,root,PetscObjectComm((PetscObject)da)));
78   PetscCall(DMDAVecRestoreArrayRead(dacoors,coors,&c));
79   PetscFunctionReturn(0);
80 }
81 
82 /*@
83    DMDAGetRay - Returns a vector on process zero that contains a row or column of the values in a DMDA vector
84 
85    Collective on DMDA
86 
87    Input Parameters:
88 +  da - the distributed array
89 .  dir - Cartesian direction, either DM_X, DM_Y, or DM_Z
90 -  gp - global grid point number in this direction
91 
92    Output Parameters:
93 +  newvec - the new vector that can hold the values (size zero on all processes except process 0)
94 -  scatter - the VecScatter that will map from the original vector to the slice
95 
96    Level: advanced
97 
98    Notes:
99    All processors that share the DMDA must call this with the same gp value
100 
101 @*/
102 PetscErrorCode  DMDAGetRay(DM da,DMDirection dir,PetscInt gp,Vec *newvec,VecScatter *scatter)
103 {
104   PetscMPIInt    rank;
105   DM_DA          *dd = (DM_DA*)da->data;
106   IS             is;
107   AO             ao;
108   Vec            vec;
109   PetscInt       *indices,i,j;
110 
111   PetscFunctionBegin;
112   PetscCheck(da->dim != 3,PetscObjectComm((PetscObject) da), PETSC_ERR_SUP, "Cannot get slice from 3d DMDA");
113   PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject) da), &rank));
114   PetscCall(DMDAGetAO(da, &ao));
115   if (rank == 0) {
116     if (da->dim == 1) {
117       if (dir == DM_X) {
118         PetscCall(PetscMalloc1(dd->w, &indices));
119         indices[0] = dd->w*gp;
120         for (i = 1; i < dd->w; ++i) indices[i] = indices[i-1] + 1;
121         PetscCall(AOApplicationToPetsc(ao, dd->w, indices));
122         PetscCall(VecCreate(PETSC_COMM_SELF, newvec));
123         PetscCall(VecSetBlockSize(*newvec, dd->w));
124         PetscCall(VecSetSizes(*newvec, dd->w, PETSC_DETERMINE));
125         PetscCall(VecSetType(*newvec, VECSEQ));
126         PetscCall(ISCreateGeneral(PETSC_COMM_SELF, dd->w, indices, PETSC_OWN_POINTER, &is));
127       } else PetscCheck(dir != DM_Y,PetscObjectComm((PetscObject) da), PETSC_ERR_SUP, "Cannot get Y slice from 1d DMDA");
128       else SETERRQ(PetscObjectComm((PetscObject) da), PETSC_ERR_ARG_OUTOFRANGE, "Unknown DMDirection");
129     } else {
130       if (dir == DM_Y) {
131         PetscCall(PetscMalloc1(dd->w*dd->M,&indices));
132         indices[0] = gp*dd->M*dd->w;
133         for (i=1; i<dd->M*dd->w; i++) indices[i] = indices[i-1] + 1;
134 
135         PetscCall(AOApplicationToPetsc(ao,dd->M*dd->w,indices));
136         PetscCall(VecCreate(PETSC_COMM_SELF,newvec));
137         PetscCall(VecSetBlockSize(*newvec,dd->w));
138         PetscCall(VecSetSizes(*newvec,dd->M*dd->w,PETSC_DETERMINE));
139         PetscCall(VecSetType(*newvec,VECSEQ));
140         PetscCall(ISCreateGeneral(PETSC_COMM_SELF,dd->w*dd->M,indices,PETSC_OWN_POINTER,&is));
141       } else if (dir == DM_X) {
142         PetscCall(PetscMalloc1(dd->w*dd->N,&indices));
143         indices[0] = dd->w*gp;
144         for (j=1; j<dd->w; j++) indices[j] = indices[j-1] + 1;
145         for (i=1; i<dd->N; i++) {
146           indices[i*dd->w] = indices[i*dd->w-1] + dd->w*dd->M - dd->w + 1;
147           for (j=1; j<dd->w; j++) indices[i*dd->w + j] = indices[i*dd->w + j - 1] + 1;
148         }
149         PetscCall(AOApplicationToPetsc(ao,dd->w*dd->N,indices));
150         PetscCall(VecCreate(PETSC_COMM_SELF,newvec));
151         PetscCall(VecSetBlockSize(*newvec,dd->w));
152         PetscCall(VecSetSizes(*newvec,dd->N*dd->w,PETSC_DETERMINE));
153         PetscCall(VecSetType(*newvec,VECSEQ));
154         PetscCall(ISCreateGeneral(PETSC_COMM_SELF,dd->w*dd->N,indices,PETSC_OWN_POINTER,&is));
155       } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Unknown DMDirection");
156     }
157   } else {
158     PetscCall(VecCreateSeq(PETSC_COMM_SELF, 0, newvec));
159     PetscCall(ISCreateGeneral(PETSC_COMM_SELF, 0, NULL, PETSC_COPY_VALUES, &is));
160   }
161   PetscCall(DMGetGlobalVector(da, &vec));
162   PetscCall(VecScatterCreate(vec, is, *newvec, NULL, scatter));
163   PetscCall(DMRestoreGlobalVector(da, &vec));
164   PetscCall(ISDestroy(&is));
165   PetscFunctionReturn(0);
166 }
167 
168 /*@C
169    DMDAGetProcessorSubset - Returns a communicator consisting only of the
170    processors in a DMDA that own a particular global x, y, or z grid point
171    (corresponding to a logical plane in a 3D grid or a line in a 2D grid).
172 
173    Collective on da
174 
175    Input Parameters:
176 +  da - the distributed array
177 .  dir - Cartesian direction, either DM_X, DM_Y, or DM_Z
178 -  gp - global grid point number in this direction
179 
180    Output Parameter:
181 .  comm - new communicator
182 
183    Level: advanced
184 
185    Notes:
186    All processors that share the DMDA must call this with the same gp value
187 
188    After use, comm should be freed with MPI_Comm_free()
189 
190    This routine is particularly useful to compute boundary conditions
191    or other application-specific calculations that require manipulating
192    sets of data throughout a logical plane of grid points.
193 
194    Not supported from Fortran
195 
196 @*/
197 PetscErrorCode  DMDAGetProcessorSubset(DM da,DMDirection dir,PetscInt gp,MPI_Comm *comm)
198 {
199   MPI_Group      group,subgroup;
200   PetscInt       i,ict,flag,*owners,xs,xm,ys,ym,zs,zm;
201   PetscMPIInt    size,*ranks = NULL;
202   DM_DA          *dd = (DM_DA*)da->data;
203 
204   PetscFunctionBegin;
205   PetscValidHeaderSpecificType(da,DM_CLASSID,1,DMDA);
206   flag = 0;
207   PetscCall(DMDAGetCorners(da,&xs,&ys,&zs,&xm,&ym,&zm));
208   PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)da),&size));
209   if (dir == DM_Z) {
210     PetscCheck(da->dim >= 3,PetscObjectComm((PetscObject)da),PETSC_ERR_ARG_OUTOFRANGE,"DM_Z invalid for DMDA dim < 3");
211     PetscCheckFalse(gp < 0 || gp > dd->P,PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"invalid grid point");
212     if (gp >= zs && gp < zs+zm) flag = 1;
213   } else if (dir == DM_Y) {
214     PetscCheck(da->dim != 1,PetscObjectComm((PetscObject)da),PETSC_ERR_ARG_OUTOFRANGE,"DM_Y invalid for DMDA dim = 1");
215     PetscCheckFalse(gp < 0 || gp > dd->N,PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"invalid grid point");
216     if (gp >= ys && gp < ys+ym) flag = 1;
217   } else if (dir == DM_X) {
218     PetscCheckFalse(gp < 0 || gp > dd->M,PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"invalid grid point");
219     if (gp >= xs && gp < xs+xm) flag = 1;
220   } else SETERRQ(PetscObjectComm((PetscObject)da),PETSC_ERR_ARG_OUTOFRANGE,"Invalid direction");
221 
222   PetscCall(PetscMalloc2(size,&owners,size,&ranks));
223   PetscCallMPI(MPI_Allgather(&flag,1,MPIU_INT,owners,1,MPIU_INT,PetscObjectComm((PetscObject)da)));
224   ict  = 0;
225   PetscCall(PetscInfo(da,"DMDAGetProcessorSubset: dim=%" PetscInt_FMT ", direction=%d, procs: ",da->dim,(int)dir));
226   for (i=0; i<size; i++) {
227     if (owners[i]) {
228       ranks[ict] = i; ict++;
229       PetscCall(PetscInfo(da,"%" PetscInt_FMT " ",i));
230     }
231   }
232   PetscCall(PetscInfo(da,"\n"));
233   PetscCallMPI(MPI_Comm_group(PetscObjectComm((PetscObject)da),&group));
234   PetscCallMPI(MPI_Group_incl(group,ict,ranks,&subgroup));
235   PetscCallMPI(MPI_Comm_create(PetscObjectComm((PetscObject)da),subgroup,comm));
236   PetscCallMPI(MPI_Group_free(&subgroup));
237   PetscCallMPI(MPI_Group_free(&group));
238   PetscCall(PetscFree2(owners,ranks));
239   PetscFunctionReturn(0);
240 }
241 
242 /*@C
243    DMDAGetProcessorSubsets - Returns communicators consisting only of the
244    processors in a DMDA adjacent in a particular dimension,
245    corresponding to a logical plane in a 3D grid or a line in a 2D grid.
246 
247    Collective on da
248 
249    Input Parameters:
250 +  da - the distributed array
251 -  dir - Cartesian direction, either DM_X, DM_Y, or DM_Z
252 
253    Output Parameter:
254 .  subcomm - new communicator
255 
256    Level: advanced
257 
258    Notes:
259    This routine is useful for distributing one-dimensional data in a tensor product grid.
260 
261    After use, comm should be freed with MPI_Comm_free()
262 
263    Not supported from Fortran
264 
265 @*/
266 PetscErrorCode  DMDAGetProcessorSubsets(DM da, DMDirection dir, MPI_Comm *subcomm)
267 {
268   MPI_Comm       comm;
269   MPI_Group      group, subgroup;
270   PetscInt       subgroupSize = 0;
271   PetscInt       *firstPoints;
272   PetscMPIInt    size, *subgroupRanks = NULL;
273   PetscInt       xs, xm, ys, ym, zs, zm, firstPoint, p;
274 
275   PetscFunctionBegin;
276   PetscValidHeaderSpecificType(da, DM_CLASSID, 1,DMDA);
277   PetscCall(PetscObjectGetComm((PetscObject)da,&comm));
278   PetscCall(DMDAGetCorners(da, &xs, &ys, &zs, &xm, &ym, &zm));
279   PetscCallMPI(MPI_Comm_size(comm, &size));
280   if (dir == DM_Z) {
281     PetscCheck(da->dim >= 3,comm,PETSC_ERR_ARG_OUTOFRANGE,"DM_Z invalid for DMDA dim < 3");
282     firstPoint = zs;
283   } else if (dir == DM_Y) {
284     PetscCheck(da->dim != 1,comm,PETSC_ERR_ARG_OUTOFRANGE,"DM_Y invalid for DMDA dim = 1");
285     firstPoint = ys;
286   } else if (dir == DM_X) {
287     firstPoint = xs;
288   } else SETERRQ(comm,PETSC_ERR_ARG_OUTOFRANGE,"Invalid direction");
289 
290   PetscCall(PetscMalloc2(size, &firstPoints, size, &subgroupRanks));
291   PetscCallMPI(MPI_Allgather(&firstPoint, 1, MPIU_INT, firstPoints, 1, MPIU_INT, comm));
292   PetscCall(PetscInfo(da,"DMDAGetProcessorSubset: dim=%" PetscInt_FMT ", direction=%d, procs: ",da->dim,(int)dir));
293   for (p = 0; p < size; ++p) {
294     if (firstPoints[p] == firstPoint) {
295       subgroupRanks[subgroupSize++] = p;
296       PetscCall(PetscInfo(da, "%" PetscInt_FMT " ", p));
297     }
298   }
299   PetscCall(PetscInfo(da, "\n"));
300   PetscCallMPI(MPI_Comm_group(comm, &group));
301   PetscCallMPI(MPI_Group_incl(group, subgroupSize, subgroupRanks, &subgroup));
302   PetscCallMPI(MPI_Comm_create(comm, subgroup, subcomm));
303   PetscCallMPI(MPI_Group_free(&subgroup));
304   PetscCallMPI(MPI_Group_free(&group));
305   PetscCall(PetscFree2(firstPoints, subgroupRanks));
306   PetscFunctionReturn(0);
307 }
308