Actual source code: ex57.c
1: static char help[] = "Reads in a binary file, extracts a submatrix from it, and writes to another binary file.\n\
2: Options:\n\
3: -fin <mat> : input matrix file\n\
4: -fout <mat> : output marrix file\n\
5: -start <row> : the row from where the submat should be extracted\n\
6: -m <sx> : the size of the submatrix\n";
8: #include <petscmat.h>
9: #include <petscvec.h>
11: int main(int argc, char **args)
12: {
13: char fin[PETSC_MAX_PATH_LEN], fout[PETSC_MAX_PATH_LEN] = "default.mat";
14: PetscViewer fdin, fdout;
15: Vec b;
16: MatType mtype = MATSEQBAIJ;
17: Mat A, *B;
18: PetscInt start = 0;
19: PetscInt m;
20: IS isrow, iscol;
21: PetscBool flg;
23: PetscFunctionBeginUser;
24: PetscCall(PetscInitialize(&argc, &args, NULL, help));
25: PetscCall(PetscOptionsGetString(NULL, NULL, "-fin", fin, sizeof(fin), &flg));
26: PetscCheck(flg, PETSC_COMM_WORLD, PETSC_ERR_USER, "Must indicate binary file with the -fin option");
27: PetscCall(PetscViewerBinaryOpen(PETSC_COMM_SELF, fin, FILE_MODE_READ, &fdin));
29: PetscCall(PetscOptionsGetString(NULL, NULL, "-fout", fout, sizeof(fout), &flg));
30: if (!flg) PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Writing submatrix to file : %s\n", fout));
31: PetscCall(PetscViewerBinaryOpen(PETSC_COMM_SELF, fout, FILE_MODE_WRITE, &fdout));
33: PetscCall(MatCreate(PETSC_COMM_SELF, &A));
34: PetscCall(MatSetType(A, mtype));
35: PetscCall(MatLoad(A, fdin));
36: PetscCall(PetscViewerDestroy(&fdin));
38: PetscCall(MatGetSize(A, &m, &m));
39: m /= 2;
40: PetscCall(PetscOptionsGetInt(NULL, NULL, "-start", &start, NULL));
41: PetscCall(PetscOptionsGetInt(NULL, NULL, "-m", &m, NULL));
43: PetscCall(ISCreateStride(PETSC_COMM_SELF, m, start, 1, &isrow));
44: PetscCall(ISCreateStride(PETSC_COMM_SELF, m, start, 1, &iscol));
45: PetscCall(MatCreateSubMatrices(A, 1, &isrow, &iscol, MAT_INITIAL_MATRIX, &B));
46: PetscCall(MatView(B[0], fdout));
48: PetscCall(VecCreate(PETSC_COMM_SELF, &b));
49: PetscCall(VecSetSizes(b, PETSC_DECIDE, m));
50: PetscCall(VecSetFromOptions(b));
51: PetscCall(MatView(B[0], fdout));
52: PetscCall(PetscViewerDestroy(&fdout));
54: PetscCall(MatDestroy(&A));
55: PetscCall(MatDestroy(&B[0]));
56: PetscCall(VecDestroy(&b));
57: PetscCall(PetscFree(B));
58: PetscCall(ISDestroy(&iscol));
59: PetscCall(ISDestroy(&isrow));
60: PetscCall(PetscFinalize());
61: return 0;
62: }
64: /*TEST
66: test:
67: args: -fin ${DATAFILESPATH}/matrices/small -fout joe -start 2 -m 4
68: requires: datafilespath double !complex !defined(PETSC_USE_64BIT_INDICES)
70: TEST*/