Actual source code: ex37.c
petsc-3.7.1 2016-05-15
2: static char help[] = "Test MatGetMultiProcBlock() and MatCreateRedundantMatrix() \n\
3: Reads a PETSc matrix and vector from a file and solves a linear system.\n\n";
4: /*
5: Example:
6: mpiexec -n 4 ./ex37 -f <input_file> -nsubcomm 2 -subcomm_view -subcomm_type <1 or 2>
7: */
9: #include <petscksp.h>
13: int main(int argc,char **args)
14: {
15: KSP subksp;
16: Mat A,subA;
17: Vec x,b,u,subb,subx,subu;
18: PetscViewer fd;
19: char file[PETSC_MAX_PATH_LEN];
20: PetscBool flg;
22: PetscInt i,m,n,its;
23: PetscReal norm;
24: PetscMPIInt rank,size;
25: MPI_Comm comm,subcomm;
26: PetscSubcomm psubcomm;
27: PetscInt nsubcomm=1,id;
28: PetscScalar *barray,*xarray,*uarray,*array,one=1.0;
29: PetscInt type=1;
31: PetscInitialize(&argc,&args,(char*)0,help);
32: /* Load the matrix */
33: PetscOptionsGetString(NULL,NULL,"-f",file,PETSC_MAX_PATH_LEN,&flg);
34: if (!flg) SETERRQ(PETSC_COMM_WORLD,1,"Must indicate binary file with the -f option");
35: PetscViewerBinaryOpen(PETSC_COMM_WORLD,file,FILE_MODE_READ,&fd);
37: /* Load the matrix; then destroy the viewer.*/
38: MatCreate(PETSC_COMM_WORLD,&A);
39: MatLoad(A,fd);
40: PetscViewerDestroy(&fd);
42: PetscObjectGetComm((PetscObject)A,&comm);
43: MPI_Comm_size(comm,&size);
44: MPI_Comm_rank(comm,&rank);
46: /* Create rhs vector b */
47: MatGetLocalSize(A,&m,NULL);
48: VecCreate(PETSC_COMM_WORLD,&b);
49: VecSetSizes(b,m,PETSC_DECIDE);
50: VecSetFromOptions(b);
51: VecSet(b,one);
53: VecDuplicate(b,&x);
54: VecDuplicate(b,&u);
55: VecSet(x,0.0);
57: /* Test MatGetMultiProcBlock() */
58: PetscOptionsGetInt(NULL,NULL,"-nsubcomm",&nsubcomm,NULL);
59: PetscOptionsGetInt(NULL,NULL,"-subcomm_type",&type,NULL);
61: PetscSubcommCreate(comm,&psubcomm);
62: PetscSubcommSetNumber(psubcomm,nsubcomm);
63: if (type == PETSC_SUBCOMM_GENERAL) { /* user provides color, subrank and duprank */
64: PetscMPIInt color,subrank,duprank,subsize;
65: duprank = size-1 - rank;
66: subsize = size/nsubcomm;
67: if (subsize*nsubcomm != size) SETERRQ2(comm,PETSC_ERR_SUP,"This example requires nsubcomm %D divides size %D",nsubcomm,size);
68: color = duprank/subsize;
69: subrank = duprank - color*subsize;
70: PetscSubcommSetTypeGeneral(psubcomm,color,subrank);
71: } else if (type == PETSC_SUBCOMM_CONTIGUOUS) {
72: PetscSubcommSetType(psubcomm,PETSC_SUBCOMM_CONTIGUOUS);
73: } else if (type == PETSC_SUBCOMM_INTERLACED) {
74: PetscSubcommSetType(psubcomm,PETSC_SUBCOMM_INTERLACED);
75: } else SETERRQ1(psubcomm->parent,PETSC_ERR_SUP,"PetscSubcommType %D is not supported yet",type);
76: PetscSubcommSetFromOptions(psubcomm);
77: subcomm = PetscSubcommChild(psubcomm);
79: /* Test MatCreateRedundantMatrix() */
80: if (size > 1) {
81: MatCreateRedundantMatrix(A,nsubcomm,subcomm,MAT_INITIAL_MATRIX,&subA);
82: MatCreateRedundantMatrix(A,nsubcomm,subcomm,MAT_REUSE_MATRIX,&subA);
83: MatDestroy(&subA);
84: }
86: /* Create subA */
87: MatGetMultiProcBlock(A,subcomm,MAT_INITIAL_MATRIX,&subA);
88: MatGetMultiProcBlock(A,subcomm,MAT_REUSE_MATRIX,&subA);
90: /* Create sub vectors without arrays. Place b's and x's local arrays into subb and subx */
91: MatGetLocalSize(subA,&m,&n);
92: VecCreateMPIWithArray(subcomm,1,m,PETSC_DECIDE,NULL,&subb);
93: VecCreateMPIWithArray(subcomm,1,n,PETSC_DECIDE,NULL,&subx);
94: VecCreateMPIWithArray(subcomm,1,n,PETSC_DECIDE,NULL,&subu);
96: VecGetArray(b,&barray);
97: VecGetArray(x,&xarray);
98: VecGetArray(u,&uarray);
99: VecPlaceArray(subb,barray);
100: VecPlaceArray(subx,xarray);
101: VecPlaceArray(subu,uarray);
103: /* Create linear solvers associated with subA */
104: KSPCreate(subcomm,&subksp);
105: KSPSetOperators(subksp,subA,subA);
106: KSPSetFromOptions(subksp);
108: /* Solve sub systems */
109: KSPSolve(subksp,subb,subx);
110: KSPGetIterationNumber(subksp,&its);
112: /* check residual */
113: MatMult(subA,subx,subu);
114: VecAXPY(subu,-1.0,subb);
115: VecNorm(u,NORM_2,&norm);
116: if (norm > 1.e-4 && !rank) {
117: PetscPrintf(PETSC_COMM_WORLD,"[%D] Number of iterations = %3D\n",rank,its);
118: printf("Error: Residual norm of each block |subb - subA*subx |= %g\n",(double)norm);
119: }
120: VecResetArray(subb);
121: VecResetArray(subx);
122: VecResetArray(subu);
124: PetscOptionsGetInt(NULL,NULL,"-subvec_view",&id,&flg);
125: if (flg && rank == id) {
126: PetscPrintf(PETSC_COMM_SELF,"[%D] subb:\n", rank);
127: VecGetArray(subb,&array);
128: for (i=0; i<m; i++) printf("%g\n",(double)PetscRealPart(array[i]));
129: VecRestoreArray(subb,&array);
130: PetscPrintf(PETSC_COMM_SELF,"[%D] subx:\n", rank);
131: VecGetArray(subx,&array);
132: for (i=0; i<m; i++) printf("%g\n",(double)PetscRealPart(array[i]));
133: VecRestoreArray(subx,&array);
134: }
136: VecRestoreArray(x,&xarray);
137: VecRestoreArray(b,&barray);
138: VecRestoreArray(u,&uarray);
139: MatDestroy(&subA);
140: VecDestroy(&subb);
141: VecDestroy(&subx);
142: VecDestroy(&subu);
143: KSPDestroy(&subksp);
144: PetscSubcommDestroy(&psubcomm);
145: MatDestroy(&A); VecDestroy(&b);
146: VecDestroy(&u); VecDestroy(&x);
148: PetscFinalize();
149: return 0;
150: }