1 static char help[] = "Test repeated LU factorizations. Used for checking memory leak\n\ 2 -m <size> : problem size\n\ 3 -mat_nonsym : use nonsymmetric matrix (default is symmetric)\n\n"; 4 5 #include <petscmat.h> 6 int main(int argc, char **args) 7 { 8 Mat C, F; /* matrix */ 9 Vec x, u, b; /* approx solution, RHS, exact solution */ 10 PetscReal norm; /* norm of solution error */ 11 PetscScalar v, none = -1.0; 12 PetscInt I, J, ldim, low, high, iglobal, Istart, Iend; 13 PetscInt i, j, m = 3, n = 2, its; 14 PetscMPIInt size, rank; 15 PetscBool mat_nonsymmetric; 16 PetscInt its_max; 17 MatFactorInfo factinfo; 18 IS perm, iperm; 19 20 PetscFunctionBeginUser; 21 PetscCall(PetscInitialize(&argc, &args, (char *)0, help)); 22 PetscCall(PetscOptionsGetInt(NULL, NULL, "-m", &m, NULL)); 23 PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank)); 24 PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size)); 25 n = 2 * size; 26 27 /* 28 Set flag if we are doing a nonsymmetric problem; the default is symmetric. 29 */ 30 PetscCall(PetscOptionsHasName(NULL, NULL, "-mat_nonsym", &mat_nonsymmetric)); 31 32 /* 33 Create parallel matrix, specifying only its global dimensions. 34 When using MatCreate(), the matrix format can be specified at 35 runtime. Also, the parallel partitioning of the matrix is 36 determined by PETSc at runtime. 37 */ 38 PetscCall(MatCreate(PETSC_COMM_WORLD, &C)); 39 PetscCall(MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n)); 40 PetscCall(MatSetFromOptions(C)); 41 PetscCall(MatGetOwnershipRange(C, &Istart, &Iend)); 42 43 /* 44 Set matrix entries matrix in parallel. 45 - Each processor needs to insert only elements that it owns 46 locally (but any non-local elements will be sent to the 47 appropriate processor during matrix assembly). 48 - Always specify global row and columns of matrix entries. 49 */ 50 for (I = Istart; I < Iend; I++) { 51 v = -1.0; 52 i = I / n; 53 j = I - i * n; 54 if (i > 0) { 55 J = I - n; 56 PetscCall(MatSetValues(C, 1, &I, 1, &J, &v, ADD_VALUES)); 57 } 58 if (i < m - 1) { 59 J = I + n; 60 PetscCall(MatSetValues(C, 1, &I, 1, &J, &v, ADD_VALUES)); 61 } 62 if (j > 0) { 63 J = I - 1; 64 PetscCall(MatSetValues(C, 1, &I, 1, &J, &v, ADD_VALUES)); 65 } 66 if (j < n - 1) { 67 J = I + 1; 68 PetscCall(MatSetValues(C, 1, &I, 1, &J, &v, ADD_VALUES)); 69 } 70 v = 4.0; 71 PetscCall(MatSetValues(C, 1, &I, 1, &I, &v, ADD_VALUES)); 72 } 73 74 /* 75 Make the matrix nonsymmetric if desired 76 */ 77 if (mat_nonsymmetric) { 78 for (I = Istart; I < Iend; I++) { 79 v = -1.5; 80 i = I / n; 81 if (i > 1) { 82 J = I - n - 1; 83 PetscCall(MatSetValues(C, 1, &I, 1, &J, &v, ADD_VALUES)); 84 } 85 } 86 } else { 87 PetscCall(MatSetOption(C, MAT_SYMMETRIC, PETSC_TRUE)); 88 PetscCall(MatSetOption(C, MAT_SYMMETRY_ETERNAL, PETSC_TRUE)); 89 } 90 91 /* 92 Assemble matrix, using the 2-step process: 93 MatAssemblyBegin(), MatAssemblyEnd() 94 Computations can be done while messages are in transition 95 by placing code between these two statements. 96 */ 97 PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY)); 98 PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY)); 99 100 its_max = 1000; 101 /* 102 Create parallel vectors. 103 - When using VecSetSizes(), we specify only the vector's global 104 dimension; the parallel partitioning is determined at runtime. 105 - Note: We form 1 vector from scratch and then duplicate as needed. 106 */ 107 PetscCall(VecCreate(PETSC_COMM_WORLD, &u)); 108 PetscCall(VecSetSizes(u, PETSC_DECIDE, m * n)); 109 PetscCall(VecSetFromOptions(u)); 110 PetscCall(VecDuplicate(u, &b)); 111 PetscCall(VecDuplicate(b, &x)); 112 113 /* 114 Currently, all parallel PETSc vectors are partitioned by 115 contiguous chunks across the processors. Determine which 116 range of entries are locally owned. 117 */ 118 PetscCall(VecGetOwnershipRange(x, &low, &high)); 119 120 /* 121 Set elements within the exact solution vector in parallel. 122 - Each processor needs to insert only elements that it owns 123 locally (but any non-local entries will be sent to the 124 appropriate processor during vector assembly). 125 - Always specify global locations of vector entries. 126 */ 127 PetscCall(VecGetLocalSize(x, &ldim)); 128 for (i = 0; i < ldim; i++) { 129 iglobal = i + low; 130 v = (PetscScalar)(i + 100 * rank); 131 PetscCall(VecSetValues(u, 1, &iglobal, &v, INSERT_VALUES)); 132 } 133 134 /* 135 Assemble vector, using the 2-step process: 136 VecAssemblyBegin(), VecAssemblyEnd() 137 Computations can be done while messages are in transition, 138 by placing code between these two statements. 139 */ 140 PetscCall(VecAssemblyBegin(u)); 141 PetscCall(VecAssemblyEnd(u)); 142 143 /* Compute right-hand-side vector */ 144 PetscCall(MatMult(C, u, b)); 145 146 PetscCall(MatGetOrdering(C, MATORDERINGNATURAL, &perm, &iperm)); 147 its_max = 2000; 148 for (i = 0; i < its_max; i++) { 149 PetscCall(MatGetFactor(C, MATSOLVERPETSC, MAT_FACTOR_LU, &F)); 150 PetscCall(MatLUFactorSymbolic(F, C, perm, iperm, &factinfo)); 151 for (j = 0; j < 1; j++) PetscCall(MatLUFactorNumeric(F, C, &factinfo)); 152 PetscCall(MatSolve(F, b, x)); 153 PetscCall(MatDestroy(&F)); 154 } 155 PetscCall(ISDestroy(&perm)); 156 PetscCall(ISDestroy(&iperm)); 157 158 /* Check the error */ 159 PetscCall(VecAXPY(x, none, u)); 160 PetscCall(VecNorm(x, NORM_2, &norm)); 161 PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Norm of error %t\n", (double)norm)); 162 163 /* Free work space. */ 164 PetscCall(VecDestroy(&u)); 165 PetscCall(VecDestroy(&x)); 166 PetscCall(VecDestroy(&b)); 167 PetscCall(MatDestroy(&C)); 168 PetscCall(PetscFinalize()); 169 return 0; 170 } 171