xref: /petsc/src/mat/tutorials/ex2.c (revision 9371c9d470a9602b6d10a8bf50c9b2280a79e45a)
1 static char help[] = "testing SeqDense matrices with an LDA (leading dimension of the user-allocated array) larger than M.\n";
2 /*
3  * Example code testing SeqDense matrices with an LDA (leading dimension
4  * of the user-allocated array) larger than M.
5  * This example tests the functionality of MatSetValues(), MatMult(),
6  * and MatMultTranspose().
7  */
8 
9 #include <petscmat.h>
10 
11 int main(int argc, char **argv) {
12   Mat          A, A11, A12, A21, A22;
13   Vec          X, X1, X2, Y, Z, Z1, Z2;
14   PetscScalar *a, *b, *x, *y, *z, v, one = 1;
15   PetscReal    nrm;
16   PetscInt     size = 8, size1 = 6, size2 = 2, i, j;
17   PetscRandom  rnd;
18 
19   PetscFunctionBeginUser;
20   PetscCall(PetscInitialize(&argc, &argv, 0, help));
21   PetscCall(PetscRandomCreate(PETSC_COMM_SELF, &rnd));
22 
23   /*
24    * Create matrix and three vectors: these are all normal
25    */
26   PetscCall(PetscMalloc1(size * size, &a));
27   PetscCall(PetscMalloc1(size * size, &b));
28   for (i = 0; i < size; i++) {
29     for (j = 0; j < size; j++) {
30       PetscCall(PetscRandomGetValue(rnd, &a[i + j * size]));
31       b[i + j * size] = a[i + j * size];
32     }
33   }
34   PetscCall(MatCreate(PETSC_COMM_SELF, &A));
35   PetscCall(MatSetSizes(A, size, size, size, size));
36   PetscCall(MatSetType(A, MATSEQDENSE));
37   PetscCall(MatSeqDenseSetPreallocation(A, a));
38   PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
39   PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
40 
41   PetscCall(PetscMalloc1(size, &x));
42   for (i = 0; i < size; i++) { x[i] = one; }
43   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, size, x, &X));
44   PetscCall(VecAssemblyBegin(X));
45   PetscCall(VecAssemblyEnd(X));
46 
47   PetscCall(PetscMalloc1(size, &y));
48   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, size, y, &Y));
49   PetscCall(VecAssemblyBegin(Y));
50   PetscCall(VecAssemblyEnd(Y));
51 
52   PetscCall(PetscMalloc1(size, &z));
53   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, size, z, &Z));
54   PetscCall(VecAssemblyBegin(Z));
55   PetscCall(VecAssemblyEnd(Z));
56 
57   /*
58    * Now create submatrices and subvectors
59    */
60   PetscCall(MatCreate(PETSC_COMM_SELF, &A11));
61   PetscCall(MatSetSizes(A11, size1, size1, size1, size1));
62   PetscCall(MatSetType(A11, MATSEQDENSE));
63   PetscCall(MatSeqDenseSetPreallocation(A11, b));
64   PetscCall(MatDenseSetLDA(A11, size));
65   PetscCall(MatAssemblyBegin(A11, MAT_FINAL_ASSEMBLY));
66   PetscCall(MatAssemblyEnd(A11, MAT_FINAL_ASSEMBLY));
67 
68   PetscCall(MatCreate(PETSC_COMM_SELF, &A12));
69   PetscCall(MatSetSizes(A12, size1, size2, size1, size2));
70   PetscCall(MatSetType(A12, MATSEQDENSE));
71   PetscCall(MatSeqDenseSetPreallocation(A12, b + size1 * size));
72   PetscCall(MatDenseSetLDA(A12, size));
73   PetscCall(MatAssemblyBegin(A12, MAT_FINAL_ASSEMBLY));
74   PetscCall(MatAssemblyEnd(A12, MAT_FINAL_ASSEMBLY));
75 
76   PetscCall(MatCreate(PETSC_COMM_SELF, &A21));
77   PetscCall(MatSetSizes(A21, size2, size1, size2, size1));
78   PetscCall(MatSetType(A21, MATSEQDENSE));
79   PetscCall(MatSeqDenseSetPreallocation(A21, b + size1));
80   PetscCall(MatDenseSetLDA(A21, size));
81   PetscCall(MatAssemblyBegin(A21, MAT_FINAL_ASSEMBLY));
82   PetscCall(MatAssemblyEnd(A21, MAT_FINAL_ASSEMBLY));
83 
84   PetscCall(MatCreate(PETSC_COMM_SELF, &A22));
85   PetscCall(MatSetSizes(A22, size2, size2, size2, size2));
86   PetscCall(MatSetType(A22, MATSEQDENSE));
87   PetscCall(MatSeqDenseSetPreallocation(A22, b + size1 * size + size1));
88   PetscCall(MatDenseSetLDA(A22, size));
89   PetscCall(MatAssemblyBegin(A22, MAT_FINAL_ASSEMBLY));
90   PetscCall(MatAssemblyEnd(A22, MAT_FINAL_ASSEMBLY));
91 
92   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, size1, x, &X1));
93   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, size2, x + size1, &X2));
94   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, size1, z, &Z1));
95   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, size2, z + size1, &Z2));
96 
97   /*
98    * Now multiple matrix times input in two ways;
99    * compare the results
100    */
101   PetscCall(MatMult(A, X, Y));
102   PetscCall(MatMult(A11, X1, Z1));
103   PetscCall(MatMultAdd(A12, X2, Z1, Z1));
104   PetscCall(MatMult(A22, X2, Z2));
105   PetscCall(MatMultAdd(A21, X1, Z2, Z2));
106   PetscCall(VecAXPY(Z, -1.0, Y));
107   PetscCall(VecNorm(Z, NORM_2, &nrm));
108   if (nrm > 100.0 * PETSC_MACHINE_EPSILON) { PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Test1; error norm=%g\n", (double)nrm)); }
109 
110   /*
111    * Next test: change both matrices
112    */
113   PetscCall(PetscRandomGetValue(rnd, &v));
114   i = 1;
115   j = size - 2;
116   PetscCall(MatSetValues(A, 1, &i, 1, &j, &v, INSERT_VALUES));
117   j -= size1;
118   PetscCall(MatSetValues(A12, 1, &i, 1, &j, &v, INSERT_VALUES));
119   PetscCall(PetscRandomGetValue(rnd, &v));
120   i = j = size1 + 1;
121   PetscCall(MatSetValues(A, 1, &i, 1, &j, &v, INSERT_VALUES));
122   i = j = 1;
123   PetscCall(MatSetValues(A22, 1, &i, 1, &j, &v, INSERT_VALUES));
124   PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
125   PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
126   PetscCall(MatAssemblyBegin(A12, MAT_FINAL_ASSEMBLY));
127   PetscCall(MatAssemblyEnd(A12, MAT_FINAL_ASSEMBLY));
128   PetscCall(MatAssemblyBegin(A22, MAT_FINAL_ASSEMBLY));
129   PetscCall(MatAssemblyEnd(A22, MAT_FINAL_ASSEMBLY));
130 
131   PetscCall(MatMult(A, X, Y));
132   PetscCall(MatMult(A11, X1, Z1));
133   PetscCall(MatMultAdd(A12, X2, Z1, Z1));
134   PetscCall(MatMult(A22, X2, Z2));
135   PetscCall(MatMultAdd(A21, X1, Z2, Z2));
136   PetscCall(VecAXPY(Z, -1.0, Y));
137   PetscCall(VecNorm(Z, NORM_2, &nrm));
138   if (nrm > 100.0 * PETSC_MACHINE_EPSILON) { PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Test2; error norm=%g\n", (double)nrm)); }
139 
140   /*
141    * Transpose product
142    */
143   PetscCall(MatMultTranspose(A, X, Y));
144   PetscCall(MatMultTranspose(A11, X1, Z1));
145   PetscCall(MatMultTransposeAdd(A21, X2, Z1, Z1));
146   PetscCall(MatMultTranspose(A22, X2, Z2));
147   PetscCall(MatMultTransposeAdd(A12, X1, Z2, Z2));
148   PetscCall(VecAXPY(Z, -1.0, Y));
149   PetscCall(VecNorm(Z, NORM_2, &nrm));
150   if (nrm > 100.0 * PETSC_MACHINE_EPSILON) { PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Test3; error norm=%g\n", (double)nrm)); }
151   PetscCall(PetscFree(a));
152   PetscCall(PetscFree(b));
153   PetscCall(PetscFree(x));
154   PetscCall(PetscFree(y));
155   PetscCall(PetscFree(z));
156   PetscCall(MatDestroy(&A));
157   PetscCall(MatDestroy(&A11));
158   PetscCall(MatDestroy(&A12));
159   PetscCall(MatDestroy(&A21));
160   PetscCall(MatDestroy(&A22));
161 
162   PetscCall(VecDestroy(&X));
163   PetscCall(VecDestroy(&Y));
164   PetscCall(VecDestroy(&Z));
165 
166   PetscCall(VecDestroy(&X1));
167   PetscCall(VecDestroy(&X2));
168   PetscCall(VecDestroy(&Z1));
169   PetscCall(VecDestroy(&Z2));
170   PetscCall(PetscRandomDestroy(&rnd));
171   PetscCall(PetscFinalize());
172   return 0;
173 }
174 
175 /*TEST
176 
177    test:
178 
179 TEST*/
180