Actual source code: ex17.c
1: /*$Id: ex17.c,v 1.21 2001/08/07 21:30:08 bsmith Exp $*/
3: static char help[] = "Tests the use of MatSolveTranspose().nn";
5: #include petscmat.h
7: int main(int argc,char **args)
8: {
9: Mat C,A;
10: int i,j,m = 5,n = 5,I,J,ierr;
11: PetscScalar v,five = 5.0,one = 1.0,mone = -1.0;
12: IS isrow,row,col;
13: Vec x,u,b;
14: PetscReal norm;
16: PetscInitialize(&argc,&args,(char *)0,help);
17: PetscOptionsGetInt(PETSC_NULL,"-m",&m,PETSC_NULL);
18: PetscOptionsGetInt(PETSC_NULL,"-n",&n,PETSC_NULL);
20: MatCreateSeqAIJ(PETSC_COMM_SELF,m*n,m*n,5,PETSC_NULL,&C);
22: /* create the matrix for the five point stencil, YET AGAIN*/
23: for (i=0; i<m; i++) {
24: for (j=0; j<n; j++) {
25: v = -1.0; I = j + n*i;
26: if (i>0) {J = I - n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
27: if (i<m-1) {J = I + n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
28: if (j>0) {J = I - 1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
29: if (j<n-1) {J = I + 1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
30: v = 4.0; MatSetValues(C,1,&I,1,&I,&v,INSERT_VALUES);
31: }
32: }
33: MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
34: MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
36: ISCreateStride(PETSC_COMM_SELF,(m*n)/2,0,2,&isrow);
37: MatZeroRows(C,isrow,&five);
39: VecCreateSeq(PETSC_COMM_SELF,m*n,&u);
40: VecDuplicate(u,&x);
41: VecDuplicate(u,&b);
42: VecSet(&one,u);
44: MatMultTranspose(C,u,b);
46: /* Set default ordering to be Quotient Minimum Degree; also read
47: orderings from the options database */
48: MatGetOrdering(C,MATORDERING_QMD,&row,&col);
50: MatLUFactorSymbolic(C,row,col,PETSC_NULL,&A);
51: MatLUFactorNumeric(C,&A);
52: MatSolveTranspose(A,b,x);
54: ISView(row,PETSC_VIEWER_STDOUT_SELF);
55: VecAXPY(&mone,u,x);
56: VecNorm(x,NORM_2,&norm);
57: PetscPrintf(PETSC_COMM_SELF,"Norm of error %gn",norm);
59: ISDestroy(row);
60: ISDestroy(col);
61: ISDestroy(isrow);
62: VecDestroy(u);
63: VecDestroy(x);
64: VecDestroy(b);
65: MatDestroy(C);
66: MatDestroy(A);
67: PetscFinalize();
68: return 0;
69: }