1 static char help[] = "Tests matrix factorization. Note that most users should\n\ 2 employ the KSP interface to the linear solvers instead of using the factorization\n\ 3 routines directly.\n\n"; 4 5 #include <petscmat.h> 6 7 int main(int argc, char **args) 8 { 9 Mat C, LU; 10 MatInfo info; 11 PetscInt i, j, m, n, Ii, J; 12 PetscScalar v, one = 1.0; 13 IS perm, iperm; 14 Vec x, u, b; 15 PetscReal norm, fill; 16 MatFactorInfo luinfo; 17 18 PetscFunctionBeginUser; 19 PetscCall(PetscInitialize(&argc, &args, (char *)0, help)); 20 21 PetscOptionsBegin(PETSC_COMM_WORLD, NULL, "Mat test ex7 options", "Mat"); 22 m = 3; 23 n = 3; 24 fill = 2.0; 25 PetscCall(PetscOptionsInt("-m", "Number of rows in grid", NULL, m, &m, NULL)); 26 PetscCall(PetscOptionsInt("-n", "Number of columns in grid", NULL, n, &n, NULL)); 27 PetscCall(PetscOptionsReal("-fill", "Expected fill ratio for factorization", NULL, fill, &fill, NULL)); 28 29 PetscOptionsEnd(); 30 31 /* Create the matrix for the five point stencil, YET AGAIN */ 32 PetscCall(MatCreate(PETSC_COMM_SELF, &C)); 33 PetscCall(MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n)); 34 PetscCall(MatSetFromOptions(C)); 35 PetscCall(MatSetUp(C)); 36 for (i = 0; i < m; i++) { 37 for (j = 0; j < n; j++) { 38 v = -1.0; 39 Ii = j + n * i; 40 if (i > 0) { 41 J = Ii - n; 42 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES)); 43 } 44 if (i < m - 1) { 45 J = Ii + n; 46 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES)); 47 } 48 if (j > 0) { 49 J = Ii - 1; 50 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES)); 51 } 52 if (j < n - 1) { 53 J = Ii + 1; 54 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES)); 55 } 56 v = 4.0; 57 PetscCall(MatSetValues(C, 1, &Ii, 1, &Ii, &v, INSERT_VALUES)); 58 } 59 } 60 PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY)); 61 PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY)); 62 PetscCall(MatGetOrdering(C, MATORDERINGRCM, &perm, &iperm)); 63 PetscCall(MatView(C, PETSC_VIEWER_STDOUT_WORLD)); 64 PetscCall(ISView(perm, PETSC_VIEWER_STDOUT_SELF)); 65 66 PetscCall(MatFactorInfoInitialize(&luinfo)); 67 68 luinfo.fill = fill; 69 luinfo.dtcol = 0.0; 70 luinfo.zeropivot = 1.e-14; 71 luinfo.pivotinblocks = 1.0; 72 73 PetscCall(MatGetFactor(C, MATSOLVERPETSC, MAT_FACTOR_LU, &LU)); 74 PetscCall(MatLUFactorSymbolic(LU, C, perm, iperm, &luinfo)); 75 PetscCall(MatLUFactorNumeric(LU, C, &luinfo)); 76 77 PetscCall(VecCreateSeq(PETSC_COMM_SELF, m * n, &u)); 78 PetscCall(VecSet(u, one)); 79 PetscCall(VecDuplicate(u, &x)); 80 PetscCall(VecDuplicate(u, &b)); 81 82 PetscCall(MatMult(C, u, b)); 83 PetscCall(MatSolve(LU, b, x)); 84 85 PetscCall(VecView(b, PETSC_VIEWER_STDOUT_SELF)); 86 PetscCall(VecView(x, PETSC_VIEWER_STDOUT_SELF)); 87 88 PetscCall(VecAXPY(x, -1.0, u)); 89 PetscCall(VecNorm(x, NORM_2, &norm)); 90 PetscCall(PetscPrintf(PETSC_COMM_SELF, "Norm of error %g\n", (double)norm)); 91 92 PetscCall(MatGetInfo(C, MAT_LOCAL, &info)); 93 PetscCall(PetscPrintf(PETSC_COMM_SELF, "original matrix nonzeros = %" PetscInt_FMT "\n", (PetscInt)info.nz_used)); 94 PetscCall(MatGetInfo(LU, MAT_LOCAL, &info)); 95 PetscCall(PetscPrintf(PETSC_COMM_SELF, "factored matrix nonzeros = %" PetscInt_FMT "\n", (PetscInt)info.nz_used)); 96 97 PetscCall(VecDestroy(&u)); 98 PetscCall(VecDestroy(&b)); 99 PetscCall(VecDestroy(&x)); 100 PetscCall(ISDestroy(&perm)); 101 PetscCall(ISDestroy(&iperm)); 102 PetscCall(MatDestroy(&C)); 103 PetscCall(MatDestroy(&LU)); 104 105 PetscCall(PetscFinalize()); 106 return 0; 107 } 108 109 /*TEST 110 111 test: 112 suffix: 1 113 filter: grep -v " MPI process" 114 115 test: 116 suffix: 2 117 args: -m 1 -n 1 -fill 0.49 118 filter: grep -v " MPI process" 119 120 TEST*/ 121