xref: /petsc/src/dm/impls/da/dasub.c (revision 58d68138c660dfb4e9f5b03334792cd4f2ffd7cc) !
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   Vec          coors;
35   DM           dacoors;
36   DMDACoor2d **c;
37   PetscInt     i, j, xs, xm, ys, ym;
38   PetscReal    d, D = PETSC_MAX_REAL, Dv;
39   PetscMPIInt  rank, root;
40 
41   PetscFunctionBegin;
42   PetscCheck(da->dim != 1, PetscObjectComm((PetscObject)da), PETSC_ERR_SUP, "Cannot get point from 1d DMDA");
43   PetscCheck(da->dim != 3, PetscObjectComm((PetscObject)da), PETSC_ERR_SUP, "Cannot get point from 3d DMDA");
44 
45   *II = -1;
46   *JJ = -1;
47 
48   PetscCall(DMGetCoordinateDM(da, &dacoors));
49   PetscCall(DMDAGetCorners(dacoors, &xs, &ys, NULL, &xm, &ym, NULL));
50   PetscCall(DMGetCoordinates(da, &coors));
51   PetscCall(DMDAVecGetArrayRead(dacoors, coors, &c));
52   for (j = ys; j < ys + ym; j++) {
53     for (i = xs; i < xs + xm; i++) {
54       d = PetscSqrtReal(PetscRealPart((c[j][i].x - x) * (c[j][i].x - x) + (c[j][i].y - y) * (c[j][i].y - y)));
55       if (d < D) {
56         D   = d;
57         *II = i;
58         *JJ = j;
59       }
60     }
61   }
62   PetscCall(MPIU_Allreduce(&D, &Dv, 1, MPIU_REAL, MPIU_MIN, PetscObjectComm((PetscObject)da)));
63   if (D != Dv) {
64     *II  = -1;
65     *JJ  = -1;
66     rank = 0;
67   } else {
68     *X = c[*JJ][*II].x;
69     *Y = c[*JJ][*II].y;
70     PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)da), &rank));
71     rank++;
72   }
73   PetscCall(MPIU_Allreduce(&rank, &root, 1, MPI_INT, MPI_SUM, PetscObjectComm((PetscObject)da)));
74   root--;
75   PetscCallMPI(MPI_Bcast(X, 1, MPIU_SCALAR, root, PetscObjectComm((PetscObject)da)));
76   PetscCallMPI(MPI_Bcast(Y, 1, MPIU_SCALAR, root, PetscObjectComm((PetscObject)da)));
77   PetscCall(DMDAVecRestoreArrayRead(dacoors, coors, &c));
78   PetscFunctionReturn(0);
79 }
80 
81 /*@
82    DMDAGetRay - Returns a vector on process zero that contains a row or column of the values in a DMDA vector
83 
84    Collective on DMDA
85 
86    Input Parameters:
87 +  da - the distributed array
88 .  dir - Cartesian direction, either DM_X, DM_Y, or DM_Z
89 -  gp - global grid point number in this direction
90 
91    Output Parameters:
92 +  newvec - the new vector that can hold the values (size zero on all processes except process 0)
93 -  scatter - the VecScatter that will map from the original vector to the slice
94 
95    Level: advanced
96 
97    Notes:
98    All processors that share the DMDA must call this with the same gp value
99 
100 @*/
101 PetscErrorCode DMDAGetRay(DM da, DMDirection dir, PetscInt gp, Vec *newvec, VecScatter *scatter) {
102   PetscMPIInt rank;
103   DM_DA      *dd = (DM_DA *)da->data;
104   IS          is;
105   AO          ao;
106   Vec         vec;
107   PetscInt   *indices, i, j;
108 
109   PetscFunctionBegin;
110   PetscCheck(da->dim != 3, PetscObjectComm((PetscObject)da), PETSC_ERR_SUP, "Cannot get slice from 3d DMDA");
111   PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)da), &rank));
112   PetscCall(DMDAGetAO(da, &ao));
113   if (rank == 0) {
114     if (da->dim == 1) {
115       if (dir == DM_X) {
116         PetscCall(PetscMalloc1(dd->w, &indices));
117         indices[0] = dd->w * gp;
118         for (i = 1; i < dd->w; ++i) indices[i] = indices[i - 1] + 1;
119         PetscCall(AOApplicationToPetsc(ao, dd->w, indices));
120         PetscCall(VecCreate(PETSC_COMM_SELF, newvec));
121         PetscCall(VecSetBlockSize(*newvec, dd->w));
122         PetscCall(VecSetSizes(*newvec, dd->w, PETSC_DETERMINE));
123         PetscCall(VecSetType(*newvec, VECSEQ));
124         PetscCall(ISCreateGeneral(PETSC_COMM_SELF, dd->w, indices, PETSC_OWN_POINTER, &is));
125       } else {
126         PetscCheck(dir != DM_Y, PetscObjectComm((PetscObject)da), PETSC_ERR_SUP, "Cannot get Y slice from 1d DMDA");
127         SETERRQ(PetscObjectComm((PetscObject)da), PETSC_ERR_ARG_OUTOFRANGE, "Unknown DMDirection");
128       }
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   MPI_Group   group, subgroup;
199   PetscInt    i, ict, flag, *owners, xs, xm, ys, ym, zs, zm;
200   PetscMPIInt size, *ranks = NULL;
201   DM_DA      *dd = (DM_DA *)da->data;
202 
203   PetscFunctionBegin;
204   PetscValidHeaderSpecificType(da, DM_CLASSID, 1, DMDA);
205   flag = 0;
206   PetscCall(DMDAGetCorners(da, &xs, &ys, &zs, &xm, &ym, &zm));
207   PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)da), &size));
208   if (dir == DM_Z) {
209     PetscCheck(da->dim >= 3, PetscObjectComm((PetscObject)da), PETSC_ERR_ARG_OUTOFRANGE, "DM_Z invalid for DMDA dim < 3");
210     PetscCheck(gp >= 0 && gp <= dd->P, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "invalid grid point");
211     if (gp >= zs && gp < zs + zm) flag = 1;
212   } else if (dir == DM_Y) {
213     PetscCheck(da->dim != 1, PetscObjectComm((PetscObject)da), PETSC_ERR_ARG_OUTOFRANGE, "DM_Y invalid for DMDA dim = 1");
214     PetscCheck(gp >= 0 && gp <= dd->N, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "invalid grid point");
215     if (gp >= ys && gp < ys + ym) flag = 1;
216   } else if (dir == DM_X) {
217     PetscCheck(gp >= 0 && gp <= dd->M, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "invalid grid point");
218     if (gp >= xs && gp < xs + xm) flag = 1;
219   } else SETERRQ(PetscObjectComm((PetscObject)da), PETSC_ERR_ARG_OUTOFRANGE, "Invalid direction");
220 
221   PetscCall(PetscMalloc2(size, &owners, size, &ranks));
222   PetscCallMPI(MPI_Allgather(&flag, 1, MPIU_INT, owners, 1, MPIU_INT, PetscObjectComm((PetscObject)da)));
223   ict = 0;
224   PetscCall(PetscInfo(da, "DMDAGetProcessorSubset: dim=%" PetscInt_FMT ", direction=%d, procs: ", da->dim, (int)dir));
225   for (i = 0; i < size; i++) {
226     if (owners[i]) {
227       ranks[ict] = i;
228       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   MPI_Comm    comm;
268   MPI_Group   group, subgroup;
269   PetscInt    subgroupSize = 0;
270   PetscInt   *firstPoints;
271   PetscMPIInt size, *subgroupRanks = NULL;
272   PetscInt    xs, xm, ys, ym, zs, zm, firstPoint, p;
273 
274   PetscFunctionBegin;
275   PetscValidHeaderSpecificType(da, DM_CLASSID, 1, DMDA);
276   PetscCall(PetscObjectGetComm((PetscObject)da, &comm));
277   PetscCall(DMDAGetCorners(da, &xs, &ys, &zs, &xm, &ym, &zm));
278   PetscCallMPI(MPI_Comm_size(comm, &size));
279   if (dir == DM_Z) {
280     PetscCheck(da->dim >= 3, comm, PETSC_ERR_ARG_OUTOFRANGE, "DM_Z invalid for DMDA dim < 3");
281     firstPoint = zs;
282   } else if (dir == DM_Y) {
283     PetscCheck(da->dim != 1, comm, PETSC_ERR_ARG_OUTOFRANGE, "DM_Y invalid for DMDA dim = 1");
284     firstPoint = ys;
285   } else if (dir == DM_X) {
286     firstPoint = xs;
287   } else SETERRQ(comm, PETSC_ERR_ARG_OUTOFRANGE, "Invalid direction");
288 
289   PetscCall(PetscMalloc2(size, &firstPoints, size, &subgroupRanks));
290   PetscCallMPI(MPI_Allgather(&firstPoint, 1, MPIU_INT, firstPoints, 1, MPIU_INT, comm));
291   PetscCall(PetscInfo(da, "DMDAGetProcessorSubset: dim=%" PetscInt_FMT ", direction=%d, procs: ", da->dim, (int)dir));
292   for (p = 0; p < size; ++p) {
293     if (firstPoints[p] == firstPoint) {
294       subgroupRanks[subgroupSize++] = p;
295       PetscCall(PetscInfo(da, "%" PetscInt_FMT " ", p));
296     }
297   }
298   PetscCall(PetscInfo(da, "\n"));
299   PetscCallMPI(MPI_Comm_group(comm, &group));
300   PetscCallMPI(MPI_Group_incl(group, subgroupSize, subgroupRanks, &subgroup));
301   PetscCallMPI(MPI_Comm_create(comm, subgroup, subcomm));
302   PetscCallMPI(MPI_Group_free(&subgroup));
303   PetscCallMPI(MPI_Group_free(&group));
304   PetscCall(PetscFree2(firstPoints, subgroupRanks));
305   PetscFunctionReturn(0);
306 }
307