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";
7
8 #include <petscmat.h>
9 #include <petscvec.h>
10
main(int argc,char ** args)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;
22
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));
28
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));
32
33 PetscCall(MatCreate(PETSC_COMM_SELF, &A));
34 PetscCall(MatSetType(A, mtype));
35 PetscCall(MatLoad(A, fdin));
36 PetscCall(PetscViewerDestroy(&fdin));
37
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));
42
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));
47
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));
53
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 }
63
64 /*TEST
65
66 test:
67 args: -fin ${DATAFILESPATH}/matrices/small -fout joe -start 2 -m 4
68 requires: datafilespath double !complex !defined(PETSC_USE_64BIT_INDICES)
69 output_file: output/empty.out
70
71 TEST*/
72