xref: /petsc/src/mat/tutorials/ex2.c (revision 609caa7c8c030312b00807b4f015fd827bb80932)
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 
main(int argc,char ** argv)11 int main(int argc, char **argv)
12 {
13   Mat          A, A11, A12, A21, A22;
14   Vec          X, X1, X2, Y, Z, Z1, Z2;
15   PetscScalar *a, *b, *x, *y, *z, v, one = 1;
16   PetscReal    nrm;
17   PetscInt     size = 8, size1 = 6, size2 = 2, i, j;
18   PetscRandom  rnd;
19 
20   PetscFunctionBeginUser;
21   PetscCall(PetscInitialize(&argc, &argv, 0, help));
22   PetscCall(PetscRandomCreate(PETSC_COMM_SELF, &rnd));
23 
24   /*
25    * Create matrix and three vectors: these are all normal
26    */
27   PetscCall(PetscMalloc1(size * size, &a));
28   PetscCall(PetscMalloc1(size * size, &b));
29   for (i = 0; i < size; i++) {
30     for (j = 0; j < size; j++) {
31       PetscCall(PetscRandomGetValue(rnd, &a[i + j * size]));
32       b[i + j * size] = a[i + j * size];
33     }
34   }
35   PetscCall(MatCreate(PETSC_COMM_SELF, &A));
36   PetscCall(MatSetSizes(A, size, size, size, size));
37   PetscCall(MatSetType(A, MATSEQDENSE));
38   PetscCall(MatSeqDenseSetPreallocation(A, a));
39   PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
40   PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
41 
42   PetscCall(PetscMalloc1(size, &x));
43   for (i = 0; i < size; i++) x[i] = one;
44   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, size, x, &X));
45   PetscCall(VecAssemblyBegin(X));
46   PetscCall(VecAssemblyEnd(X));
47 
48   PetscCall(PetscMalloc1(size, &y));
49   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, size, y, &Y));
50   PetscCall(VecAssemblyBegin(Y));
51   PetscCall(VecAssemblyEnd(Y));
52 
53   PetscCall(PetscMalloc1(size, &z));
54   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, size, z, &Z));
55   PetscCall(VecAssemblyBegin(Z));
56   PetscCall(VecAssemblyEnd(Z));
57 
58   /*
59    * Now create submatrices and subvectors
60    */
61   PetscCall(MatCreate(PETSC_COMM_SELF, &A11));
62   PetscCall(MatSetSizes(A11, size1, size1, size1, size1));
63   PetscCall(MatSetType(A11, MATSEQDENSE));
64   PetscCall(MatSeqDenseSetPreallocation(A11, b));
65   PetscCall(MatDenseSetLDA(A11, size));
66   PetscCall(MatAssemblyBegin(A11, MAT_FINAL_ASSEMBLY));
67   PetscCall(MatAssemblyEnd(A11, MAT_FINAL_ASSEMBLY));
68 
69   PetscCall(MatCreate(PETSC_COMM_SELF, &A12));
70   PetscCall(MatSetSizes(A12, size1, size2, size1, size2));
71   PetscCall(MatSetType(A12, MATSEQDENSE));
72   PetscCall(MatSeqDenseSetPreallocation(A12, b + size1 * size));
73   PetscCall(MatDenseSetLDA(A12, size));
74   PetscCall(MatAssemblyBegin(A12, MAT_FINAL_ASSEMBLY));
75   PetscCall(MatAssemblyEnd(A12, MAT_FINAL_ASSEMBLY));
76 
77   PetscCall(MatCreate(PETSC_COMM_SELF, &A21));
78   PetscCall(MatSetSizes(A21, size2, size1, size2, size1));
79   PetscCall(MatSetType(A21, MATSEQDENSE));
80   PetscCall(MatSeqDenseSetPreallocation(A21, b + size1));
81   PetscCall(MatDenseSetLDA(A21, size));
82   PetscCall(MatAssemblyBegin(A21, MAT_FINAL_ASSEMBLY));
83   PetscCall(MatAssemblyEnd(A21, MAT_FINAL_ASSEMBLY));
84 
85   PetscCall(MatCreate(PETSC_COMM_SELF, &A22));
86   PetscCall(MatSetSizes(A22, size2, size2, size2, size2));
87   PetscCall(MatSetType(A22, MATSEQDENSE));
88   PetscCall(MatSeqDenseSetPreallocation(A22, b + size1 * size + size1));
89   PetscCall(MatDenseSetLDA(A22, size));
90   PetscCall(MatAssemblyBegin(A22, MAT_FINAL_ASSEMBLY));
91   PetscCall(MatAssemblyEnd(A22, MAT_FINAL_ASSEMBLY));
92 
93   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, size1, x, &X1));
94   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, size2, x + size1, &X2));
95   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, size1, z, &Z1));
96   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, size2, z + size1, &Z2));
97 
98   /*
99    * Now multiple matrix times input in two ways;
100    * compare the results
101    */
102   PetscCall(MatMult(A, X, Y));
103   PetscCall(MatMult(A11, X1, Z1));
104   PetscCall(MatMultAdd(A12, X2, Z1, Z1));
105   PetscCall(MatMult(A22, X2, Z2));
106   PetscCall(MatMultAdd(A21, X1, Z2, Z2));
107   PetscCall(VecAXPY(Z, -1.0, Y));
108   PetscCall(VecNorm(Z, NORM_2, &nrm));
109   if (nrm > 100.0 * PETSC_MACHINE_EPSILON) PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Test1; error norm=%g\n", (double)nrm));
110 
111   /*
112    * Next test: change both matrices
113    */
114   PetscCall(PetscRandomGetValue(rnd, &v));
115   i = 1;
116   j = size - 2;
117   PetscCall(MatSetValues(A, 1, &i, 1, &j, &v, INSERT_VALUES));
118   j -= size1;
119   PetscCall(MatSetValues(A12, 1, &i, 1, &j, &v, INSERT_VALUES));
120   PetscCall(PetscRandomGetValue(rnd, &v));
121   i = j = size1 + 1;
122   PetscCall(MatSetValues(A, 1, &i, 1, &j, &v, INSERT_VALUES));
123   i = j = 1;
124   PetscCall(MatSetValues(A22, 1, &i, 1, &j, &v, INSERT_VALUES));
125   PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
126   PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
127   PetscCall(MatAssemblyBegin(A12, MAT_FINAL_ASSEMBLY));
128   PetscCall(MatAssemblyEnd(A12, MAT_FINAL_ASSEMBLY));
129   PetscCall(MatAssemblyBegin(A22, MAT_FINAL_ASSEMBLY));
130   PetscCall(MatAssemblyEnd(A22, MAT_FINAL_ASSEMBLY));
131 
132   PetscCall(MatMult(A, X, Y));
133   PetscCall(MatMult(A11, X1, Z1));
134   PetscCall(MatMultAdd(A12, X2, Z1, Z1));
135   PetscCall(MatMult(A22, X2, Z2));
136   PetscCall(MatMultAdd(A21, X1, Z2, Z2));
137   PetscCall(VecAXPY(Z, -1.0, Y));
138   PetscCall(VecNorm(Z, NORM_2, &nrm));
139   if (nrm > 100.0 * PETSC_MACHINE_EPSILON) PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Test2; error norm=%g\n", (double)nrm));
140 
141   /*
142    * Transpose product
143    */
144   PetscCall(MatMultTranspose(A, X, Y));
145   PetscCall(MatMultTranspose(A11, X1, Z1));
146   PetscCall(MatMultTransposeAdd(A21, X2, Z1, Z1));
147   PetscCall(MatMultTranspose(A22, X2, Z2));
148   PetscCall(MatMultTransposeAdd(A12, X1, Z2, Z2));
149   PetscCall(VecAXPY(Z, -1.0, Y));
150   PetscCall(VecNorm(Z, NORM_2, &nrm));
151   if (nrm > 100.0 * PETSC_MACHINE_EPSILON) PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Test3; error norm=%g\n", (double)nrm));
152   PetscCall(PetscFree(a));
153   PetscCall(PetscFree(b));
154   PetscCall(PetscFree(x));
155   PetscCall(PetscFree(y));
156   PetscCall(PetscFree(z));
157   PetscCall(MatDestroy(&A));
158   PetscCall(MatDestroy(&A11));
159   PetscCall(MatDestroy(&A12));
160   PetscCall(MatDestroy(&A21));
161   PetscCall(MatDestroy(&A22));
162 
163   PetscCall(VecDestroy(&X));
164   PetscCall(VecDestroy(&Y));
165   PetscCall(VecDestroy(&Z));
166 
167   PetscCall(VecDestroy(&X1));
168   PetscCall(VecDestroy(&X2));
169   PetscCall(VecDestroy(&Z1));
170   PetscCall(VecDestroy(&Z2));
171   PetscCall(PetscRandomDestroy(&rnd));
172   PetscCall(PetscFinalize());
173   return 0;
174 }
175 
176 /*TEST
177 
178    test:
179      output_file: output/empty.out
180 
181 TEST*/
182