Actual source code: ex57.c
2: static char help[] = "Reads in a binary file, extracts a submatrix from it, and writes to another binary file.\n\
3: Options:\n\
4: -fin <mat> : input matrix file\n\
5: -fout <mat> : output marrix file\n\
6: -start <row> : the row from where the submat should be extracted\n\
7: -m <sx> : the size of the submatrix\n";
9: #include <petscmat.h>
10: #include <petscvec.h>
12: int main(int argc, char **args)
13: {
14: char fin[PETSC_MAX_PATH_LEN], fout[PETSC_MAX_PATH_LEN] = "default.mat";
15: PetscViewer fdin, fdout;
16: Vec b;
17: MatType mtype = MATSEQBAIJ;
18: Mat A, *B;
19: PetscInt start = 0;
20: PetscInt m;
21: IS isrow, iscol;
22: PetscBool flg;
24: PetscFunctionBeginUser;
25: PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
26: PetscCall(PetscOptionsGetString(NULL, NULL, "-fin", fin, sizeof(fin), &flg));
27: PetscCheck(flg, PETSC_COMM_WORLD, PETSC_ERR_USER, "Must indicate binary file with the -fin option");
28: PetscCall(PetscViewerBinaryOpen(PETSC_COMM_SELF, fin, FILE_MODE_READ, &fdin));
30: PetscCall(PetscOptionsGetString(NULL, NULL, "-fout", fout, sizeof(fout), &flg));
31: if (!flg) PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Writing submatrix to file : %s\n", fout));
32: PetscCall(PetscViewerBinaryOpen(PETSC_COMM_SELF, fout, FILE_MODE_WRITE, &fdout));
34: PetscCall(MatCreate(PETSC_COMM_SELF, &A));
35: PetscCall(MatSetType(A, mtype));
36: PetscCall(MatLoad(A, fdin));
37: PetscCall(PetscViewerDestroy(&fdin));
39: PetscCall(MatGetSize(A, &m, &m));
40: m /= 2;
41: PetscCall(PetscOptionsGetInt(NULL, NULL, "-start", &start, NULL));
42: PetscCall(PetscOptionsGetInt(NULL, NULL, "-m", &m, NULL));
44: PetscCall(ISCreateStride(PETSC_COMM_SELF, m, start, 1, &isrow));
45: PetscCall(ISCreateStride(PETSC_COMM_SELF, m, start, 1, &iscol));
46: PetscCall(MatCreateSubMatrices(A, 1, &isrow, &iscol, MAT_INITIAL_MATRIX, &B));
47: PetscCall(MatView(B[0], fdout));
49: PetscCall(VecCreate(PETSC_COMM_SELF, &b));
50: PetscCall(VecSetSizes(b, PETSC_DECIDE, m));
51: PetscCall(VecSetFromOptions(b));
52: PetscCall(MatView(B[0], fdout));
53: PetscCall(PetscViewerDestroy(&fdout));
55: PetscCall(MatDestroy(&A));
56: PetscCall(MatDestroy(&B[0]));
57: PetscCall(VecDestroy(&b));
58: PetscCall(PetscFree(B));
59: PetscCall(ISDestroy(&iscol));
60: PetscCall(ISDestroy(&isrow));
61: PetscCall(PetscFinalize());
62: return 0;
63: }
65: /*TEST
67: test:
68: args: -fin ${DATAFILESPATH}/matrices/small -fout joe -start 2 -m 4
69: requires: datafilespath double !complex !defined(PETSC_USE_64BIT_INDICES)
71: TEST*/