1 2 static char help[] = "Reads a matrix from PETSc binary file. Use for view or investigating matrix data structure. \n\n"; 3 /* 4 Example: 5 ./ex16 -f <matrix file> -a_mat_view draw -draw_pause -1 6 ./ex16 -f <matrix file> -a_mat_view ascii::ascii_info 7 */ 8 9 #include <petscmat.h> 10 int main(int argc, char **args) { 11 Mat A, Asp; 12 PetscViewer fd; /* viewer */ 13 char file[PETSC_MAX_PATH_LEN]; /* input file name */ 14 PetscInt m, n, rstart, rend; 15 PetscBool flg; 16 PetscInt row, ncols, j, nrows, nnzA = 0, nnzAsp = 0; 17 const PetscInt *cols; 18 const PetscScalar *vals; 19 PetscReal norm, percent, val, dtol = 1.e-16; 20 PetscMPIInt rank; 21 MatInfo matinfo; 22 PetscInt Dnnz, Onnz; 23 24 PetscFunctionBeginUser; 25 PetscCall(PetscInitialize(&argc, &args, (char *)0, help)); 26 PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank)); 27 28 /* Determine files from which we read the linear systems. */ 29 PetscCall(PetscOptionsGetString(NULL, NULL, "-f", file, sizeof(file), &flg)); 30 PetscCheck(flg, PETSC_COMM_WORLD, PETSC_ERR_USER, "Must indicate binary file with the -f option"); 31 32 /* Open binary file. Note that we use FILE_MODE_READ to indicate 33 reading from this file. */ 34 PetscCall(PetscViewerBinaryOpen(PETSC_COMM_WORLD, file, FILE_MODE_READ, &fd)); 35 36 /* Load the matrix; then destroy the viewer. */ 37 PetscCall(MatCreate(PETSC_COMM_WORLD, &A)); 38 PetscCall(MatSetOptionsPrefix(A, "a_")); 39 PetscCall(MatSetFromOptions(A)); 40 PetscCall(MatLoad(A, fd)); 41 PetscCall(PetscViewerDestroy(&fd)); 42 PetscCall(MatGetSize(A, &m, &n)); 43 PetscCall(MatGetInfo(A, MAT_LOCAL, &matinfo)); 44 /*printf("matinfo.nz_used %g\n",matinfo.nz_used);*/ 45 46 /* Get a sparse matrix Asp by dumping zero entries of A */ 47 PetscCall(MatCreate(PETSC_COMM_WORLD, &Asp)); 48 PetscCall(MatSetSizes(Asp, m, n, PETSC_DECIDE, PETSC_DECIDE)); 49 PetscCall(MatSetOptionsPrefix(Asp, "asp_")); 50 PetscCall(MatSetFromOptions(Asp)); 51 Dnnz = (PetscInt)matinfo.nz_used / m + 1; 52 Onnz = Dnnz / 2; 53 printf("Dnnz %d %d\n", Dnnz, Onnz); 54 PetscCall(MatSeqAIJSetPreallocation(Asp, Dnnz, NULL)); 55 PetscCall(MatMPIAIJSetPreallocation(Asp, Dnnz, NULL, Onnz, NULL)); 56 /* The allocation above is approximate so we must set this option to be permissive. 57 * Real code should preallocate exactly. */ 58 PetscCall(MatSetOption(Asp, MAT_NEW_NONZERO_LOCATION_ERR, PETSC_FALSE)); 59 60 /* Check zero rows */ 61 PetscCall(MatGetOwnershipRange(A, &rstart, &rend)); 62 nrows = 0; 63 for (row = rstart; row < rend; row++) { 64 PetscCall(MatGetRow(A, row, &ncols, &cols, &vals)); 65 nnzA += ncols; 66 norm = 0.0; 67 for (j = 0; j < ncols; j++) { 68 val = PetscAbsScalar(vals[j]); 69 if (norm < val) norm = norm; 70 if (val > dtol) { 71 PetscCall(MatSetValues(Asp, 1, &row, 1, &cols[j], &vals[j], INSERT_VALUES)); 72 nnzAsp++; 73 } 74 } 75 if (!norm) nrows++; 76 PetscCall(MatRestoreRow(A, row, &ncols, &cols, &vals)); 77 } 78 PetscCall(MatAssemblyBegin(Asp, MAT_FINAL_ASSEMBLY)); 79 PetscCall(MatAssemblyEnd(Asp, MAT_FINAL_ASSEMBLY)); 80 81 percent = (PetscReal)nnzA * 100 / (m * n); 82 PetscCall(PetscPrintf(PETSC_COMM_SELF, " [%d] Matrix A local size %d,%d; nnzA %d, %g percent; No. of zero rows: %d\n", rank, m, n, nnzA, percent, nrows)); 83 percent = (PetscReal)nnzAsp * 100 / (m * n); 84 PetscCall(PetscPrintf(PETSC_COMM_SELF, " [%d] Matrix Asp nnzAsp %d, %g percent\n", rank, nnzAsp, percent)); 85 86 /* investigate matcoloring for Asp */ 87 PetscBool Asp_coloring = PETSC_FALSE; 88 PetscCall(PetscOptionsHasName(NULL, NULL, "-Asp_color", &Asp_coloring)); 89 if (Asp_coloring) { 90 MatColoring mc; 91 ISColoring iscoloring; 92 MatFDColoring matfdcoloring; 93 PetscCall(PetscPrintf(PETSC_COMM_WORLD, " Create coloring of Asp...\n")); 94 PetscCall(MatColoringCreate(Asp, &mc)); 95 PetscCall(MatColoringSetType(mc, MATCOLORINGSL)); 96 PetscCall(MatColoringSetFromOptions(mc)); 97 PetscCall(MatColoringApply(mc, &iscoloring)); 98 PetscCall(MatColoringDestroy(&mc)); 99 PetscCall(MatFDColoringCreate(Asp, iscoloring, &matfdcoloring)); 100 PetscCall(MatFDColoringSetFromOptions(matfdcoloring)); 101 PetscCall(MatFDColoringSetUp(Asp, iscoloring, matfdcoloring)); 102 /*PetscCall(MatFDColoringView(matfdcoloring,PETSC_VIEWER_STDOUT_WORLD));*/ 103 PetscCall(ISColoringDestroy(&iscoloring)); 104 PetscCall(MatFDColoringDestroy(&matfdcoloring)); 105 } 106 107 /* Write Asp in binary for study - see ~petsc/src/mat/tests/ex124.c */ 108 PetscBool Asp_write = PETSC_FALSE; 109 PetscCall(PetscOptionsHasName(NULL, NULL, "-Asp_write", &Asp_write)); 110 if (Asp_write) { 111 PetscViewer viewer; 112 PetscCall(PetscPrintf(PETSC_COMM_SELF, "Write Asp into file Asp.dat ...\n")); 113 PetscCall(PetscViewerBinaryOpen(PETSC_COMM_WORLD, "Asp.dat", FILE_MODE_WRITE, &viewer)); 114 PetscCall(MatView(Asp, viewer)); 115 PetscCall(PetscViewerDestroy(&viewer)); 116 } 117 118 PetscCall(MatDestroy(&A)); 119 PetscCall(MatDestroy(&Asp)); 120 PetscCall(PetscFinalize()); 121 return 0; 122 } 123