xref: /petsc/src/mat/tutorials/ex8.c (revision 9371c9d470a9602b6d10a8bf50c9b2280a79e45a)
1 
2 static char help[] = "Shows how to add a new MatOperation to AIJ MatType\n\n";
3 
4 #include <petscmat.h>
5 #include <petscblaslapack.h>
6 
7 static PetscErrorCode MatScaleUserImpl_SeqAIJ(Mat inA, PetscScalar alpha) {
8   PetscFunctionBegin;
9   PetscCall(MatScale(inA, alpha));
10   PetscFunctionReturn(0);
11 }
12 
13 extern PetscErrorCode MatScaleUserImpl(Mat, PetscScalar);
14 
15 static PetscErrorCode MatScaleUserImpl_MPIAIJ(Mat A, PetscScalar aa) {
16   Mat AA, AB;
17 
18   PetscFunctionBegin;
19   PetscCall(MatMPIAIJGetSeqAIJ(A, &AA, &AB, NULL));
20   PetscCall(MatScaleUserImpl(AA, aa));
21   PetscCall(MatScaleUserImpl(AB, aa));
22   PetscFunctionReturn(0);
23 }
24 
25 /* This routine registers MatScaleUserImpl_SeqAIJ() and
26    MatScaleUserImpl_MPIAIJ() as methods providing MatScaleUserImpl()
27    functionality for SeqAIJ and MPIAIJ matrix-types */
28 PetscErrorCode RegisterMatScaleUserImpl(Mat mat) {
29   PetscMPIInt size;
30 
31   PetscFunctionBegin;
32   PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)mat), &size));
33   if (size == 1) { /* SeqAIJ Matrix */
34     PetscCall(PetscObjectComposeFunction((PetscObject)mat, "MatScaleUserImpl_C", MatScaleUserImpl_SeqAIJ));
35   } else { /* MPIAIJ Matrix */
36     Mat AA, AB;
37     PetscCall(MatMPIAIJGetSeqAIJ(mat, &AA, &AB, NULL));
38     PetscCall(PetscObjectComposeFunction((PetscObject)mat, "MatScaleUserImpl_C", MatScaleUserImpl_MPIAIJ));
39     PetscCall(PetscObjectComposeFunction((PetscObject)AA, "MatScaleUserImpl_C", MatScaleUserImpl_SeqAIJ));
40     PetscCall(PetscObjectComposeFunction((PetscObject)AB, "MatScaleUserImpl_C", MatScaleUserImpl_SeqAIJ));
41   }
42   PetscFunctionReturn(0);
43 }
44 
45 /* This routine deregisters MatScaleUserImpl_SeqAIJ() and
46    MatScaleUserImpl_MPIAIJ() as methods providing MatScaleUserImpl()
47    functionality for SeqAIJ and MPIAIJ matrix-types */
48 PetscErrorCode DeRegisterMatScaleUserImpl(Mat mat) {
49   PetscMPIInt size;
50 
51   PetscFunctionBegin;
52   PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)mat), &size));
53   if (size == 1) { /* SeqAIJ Matrix */
54     PetscCall(PetscObjectComposeFunction((PetscObject)mat, "MatScaleUserImpl_C", NULL));
55   } else { /* MPIAIJ Matrix */
56     Mat AA, AB;
57     PetscCall(MatMPIAIJGetSeqAIJ(mat, &AA, &AB, NULL));
58     PetscCall(PetscObjectComposeFunction((PetscObject)mat, "MatScaleUserImpl_C", NULL));
59     PetscCall(PetscObjectComposeFunction((PetscObject)AA, "MatScaleUserImpl_C", NULL));
60     PetscCall(PetscObjectComposeFunction((PetscObject)AB, "MatScaleUserImpl_C", NULL));
61   }
62   PetscFunctionReturn(0);
63 }
64 
65 /* this routines queries the already registered MatScaleUserImp_XXX
66    implementations for the given matrix, and calls the correct
67    routine. i.e if MatType is SeqAIJ, MatScaleUserImpl_SeqAIJ() gets
68    called, and if MatType is MPIAIJ, MatScaleUserImpl_MPIAIJ() gets
69    called */
70 PetscErrorCode MatScaleUserImpl(Mat mat, PetscScalar a) {
71   PetscErrorCode (*f)(Mat, PetscScalar);
72 
73   PetscFunctionBegin;
74   PetscCall(PetscObjectQueryFunction((PetscObject)mat, "MatScaleUserImpl_C", &f));
75   if (f) PetscCall((*f)(mat, a));
76   PetscFunctionReturn(0);
77 }
78 
79 /* Main user code that uses MatScaleUserImpl() */
80 
81 int main(int argc, char **args) {
82   Mat         mat;
83   PetscInt    i, j, m = 2, n, Ii, J;
84   PetscScalar v, none = -1.0;
85   PetscMPIInt rank, size;
86 
87   PetscFunctionBeginUser;
88   PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
89   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
90   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
91   n = 2 * size;
92 
93   /* create the matrix */
94   PetscCall(MatCreate(PETSC_COMM_WORLD, &mat));
95   PetscCall(MatSetSizes(mat, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n));
96   PetscCall(MatSetType(mat, MATAIJ));
97   PetscCall(MatSetUp(mat));
98 
99   /* register user defined MatScaleUser() operation for both SeqAIJ
100      and MPIAIJ types */
101   PetscCall(RegisterMatScaleUserImpl(mat));
102 
103   /* assemble the matrix */
104   for (i = 0; i < m; i++) {
105     for (j = 2 * rank; j < 2 * rank + 2; j++) {
106       v  = -1.0;
107       Ii = j + n * i;
108       if (i > 0) {
109         J = Ii - n;
110         PetscCall(MatSetValues(mat, 1, &Ii, 1, &J, &v, INSERT_VALUES));
111       }
112       if (i < m - 1) {
113         J = Ii + n;
114         PetscCall(MatSetValues(mat, 1, &Ii, 1, &J, &v, INSERT_VALUES));
115       }
116       if (j > 0) {
117         J = Ii - 1;
118         PetscCall(MatSetValues(mat, 1, &Ii, 1, &J, &v, INSERT_VALUES));
119       }
120       if (j < n - 1) {
121         J = Ii + 1;
122         PetscCall(MatSetValues(mat, 1, &Ii, 1, &J, &v, INSERT_VALUES));
123       }
124       v = 4.0;
125       PetscCall(MatSetValues(mat, 1, &Ii, 1, &Ii, &v, INSERT_VALUES));
126     }
127   }
128   PetscCall(MatAssemblyBegin(mat, MAT_FINAL_ASSEMBLY));
129   PetscCall(MatAssemblyEnd(mat, MAT_FINAL_ASSEMBLY));
130 
131   /* check the matrix before and after scaling by -1.0 */
132   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Matrix _before_ MatScaleUserImpl() operation\n"));
133   PetscCall(MatView(mat, PETSC_VIEWER_STDOUT_WORLD));
134   PetscCall(MatScaleUserImpl(mat, none));
135   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Matrix _after_ MatScaleUserImpl() operation\n"));
136   PetscCall(MatView(mat, PETSC_VIEWER_STDOUT_WORLD));
137 
138   /* deregister user defined MatScaleUser() operation for both SeqAIJ
139      and MPIAIJ types */
140   PetscCall(DeRegisterMatScaleUserImpl(mat));
141   PetscCall(MatDestroy(&mat));
142   PetscCall(PetscFinalize());
143   return 0;
144 }
145 
146 /*TEST
147 
148    test:
149 
150    test:
151       suffix: 2
152       nsize: 2
153 
154 TEST*/
155