Actual source code: ex18.c
2: #if !defined(PETSC_USE_COMPLEX)
4: static char help[] = "Reads a PETSc matrix and vector from a file and solves a linear system.\n\
5: Input arguments are:\n\
6: -f <input_file> : file to load. For a 5X5 example of the 5-pt. stencil,\n\
7: use the file petsc/src/mat/examples/matbinary.ex\n\n";
9: #include petscmat.h
10: #include petscksp.h
14: int main(int argc,char **args)
15: {
17: PetscInt its,m,n,mvec;
18: PetscLogDouble time1,time2,time;
19: PetscReal norm;
20: Vec x,b,u;
21: Mat A;
22: KSP ksp;
23: char file[PETSC_MAX_PATH_LEN];
24: PetscViewer fd;
25: PetscLogStage stage1;
26:
27: PetscInitialize(&argc,&args,(char *)0,help);
29: /* Read matrix and RHS */
30: PetscOptionsGetString(PETSC_NULL,"-f",file,PETSC_MAX_PATH_LEN-1,PETSC_NULL);
31: PetscViewerBinaryOpen(PETSC_COMM_WORLD,file,FILE_MODE_READ,&fd);
32: MatLoad(fd,MATSEQAIJ,&A);
33: VecLoad(fd,PETSC_NULL,&b);
34: PetscViewerDestroy(fd);
36: /*
37: If the load matrix is larger then the vector, due to being padded
38: to match the blocksize then create a new padded vector
39: */
40: MatGetSize(A,&m,&n);
41: VecGetSize(b,&mvec);
42: if (m > mvec) {
43: Vec tmp;
44: PetscScalar *bold,*bnew;
45: /* create a new vector b by padding the old one */
46: VecCreate(PETSC_COMM_WORLD,&tmp);
47: VecSetSizes(tmp,PETSC_DECIDE,m);
48: VecSetFromOptions(tmp);
49: VecGetArray(tmp,&bnew);
50: VecGetArray(b,&bold);
51: PetscMemcpy(bnew,bold,mvec*sizeof(PetscScalar));
52: VecDestroy(b);
53: b = tmp;
54: }
56: /* Set up solution */
57: VecDuplicate(b,&x);
58: VecDuplicate(b,&u);
59: VecSet(x,0.0);
61: /* Solve system */
62: PetscLogStageRegister("Stage 1",&stage1);
63: PetscLogStagePush(stage1);
64: KSPCreate(PETSC_COMM_WORLD,&ksp);
65: KSPSetOperators(ksp,A,A,DIFFERENT_NONZERO_PATTERN);
66: KSPSetFromOptions(ksp);
67: PetscGetTime(&time1);
68: KSPSolve(ksp,b,x);
69: PetscGetTime(&time2);
70: time = time2 - time1;
71: PetscLogStagePop();
73: /* Show result */
74: MatMult(A,x,u);
75: VecAXPY(u,-1.0,b);
76: VecNorm(u,NORM_2,&norm);
77: KSPGetIterationNumber(ksp,&its);
78: PetscPrintf(PETSC_COMM_WORLD,"Number of iterations = %3D\n",its);
79: PetscPrintf(PETSC_COMM_WORLD,"Residual norm %A\n",norm);
80: PetscPrintf(PETSC_COMM_WORLD,"Time for solve = %5.2f seconds\n",time);
82: /* Cleanup */
83: KSPDestroy(ksp);
84: VecDestroy(x);
85: VecDestroy(b);
86: VecDestroy(u);
87: MatDestroy(A);
89: PetscFinalize();
90: return 0;
91: }
93: #else
94: #include <stdio.h>
95: int main(int argc,char **args)
96: {
97: fprintf(stdout,"This example does not work for complex numbers.\n");
98: return 0;
99: }
100: #endif