Actual source code: ex6.c

petsc-3.3-p6 2013-02-11
  2: static char help[] = "Reads a PETSc matrix and vector from a file and solves a linear system.\n\
  3: Input arguments are:\n\
  4:   -f <input_file> : file to load. For example see $PETSC_DIR/share/petsc/datafiles/matrices\n\n";

  6: #include <petscksp.h>
  7: #include <petsclog.h>

 11: int main(int argc,char **args)
 12: {
 13: #if !defined(PETSC_USE_COMPLEX)
 15:   PetscInt       its;
 16:   PetscLogStage  stage1,stage2;
 17:   PetscReal      norm;
 18:   PetscLogDouble tsetup1,tsetup2,tsetup,tsolve1,tsolve2,tsolve;
 19:   Vec            x,b,u;
 20:   Mat            A;
 21:   char           file[PETSC_MAX_PATH_LEN];
 22:   PetscViewer    fd;
 23:   PetscBool      table = PETSC_FALSE,flg;
 24:   KSP            ksp;
 25: #endif

 27:   PetscInitialize(&argc,&args,(char *)0,help);

 29: #if defined(PETSC_USE_COMPLEX)
 30:   SETERRQ(PETSC_COMM_WORLD,1,"This example does not work with complex numbers");
 31: #else
 32:   PetscOptionsGetBool(PETSC_NULL,"-table",&table,PETSC_NULL);


 35:   /* Read matrix and RHS */
 36:   PetscOptionsGetString(PETSC_NULL,"-f",file,PETSC_MAX_PATH_LEN,&flg);
 37:   if (!flg) SETERRQ(PETSC_COMM_WORLD,1,"Must indicate binary file with the -f option");
 38:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,file,FILE_MODE_READ,&fd);
 39:   MatCreate(PETSC_COMM_WORLD,&A);
 40:   MatLoad(A,fd);
 41:   VecCreate(PETSC_COMM_WORLD,&b);
 42:   VecLoad(b,fd);
 43:   PetscViewerDestroy(&fd);

 45:   /* 
 46:    If the load matrix is larger then the vector, due to being padded 
 47:    to match the blocksize then create a new padded vector
 48:   */
 49:   {
 50:     PetscInt    m,n,j,mvec,start,end,indx;
 51:     Vec         tmp;
 52:     PetscScalar *bold;

 54:     MatGetLocalSize(A,&m,&n);
 55:     VecCreate(PETSC_COMM_WORLD,&tmp);
 56:     VecSetSizes(tmp,m,PETSC_DECIDE);
 57:     VecSetFromOptions(tmp);
 58:     VecGetOwnershipRange(b,&start,&end);
 59:     VecGetLocalSize(b,&mvec);
 60:     VecGetArray(b,&bold);
 61:     for (j=0; j<mvec; j++) {
 62:       indx = start+j;
 63:       VecSetValues(tmp,1,&indx,bold+j,INSERT_VALUES);
 64:     }
 65:     VecRestoreArray(b,&bold);
 66:     VecDestroy(&b);
 67:     VecAssemblyBegin(tmp);
 68:     VecAssemblyEnd(tmp);
 69:     b = tmp;
 70:   }
 71:   VecDuplicate(b,&x);
 72:   VecDuplicate(b,&u);

 74:   VecSet(x,0.0);
 75:   PetscBarrier((PetscObject)A);

 77:   PetscLogStageRegister("mystage 1",&stage1);
 78:   PetscLogStagePush(stage1);
 79:   PetscGetTime(&tsetup1);
 80:   KSPCreate(PETSC_COMM_WORLD,&ksp);
 81:   KSPSetOperators(ksp,A,A,DIFFERENT_NONZERO_PATTERN);
 82:   KSPSetFromOptions(ksp);
 83:   KSPSetUp(ksp);
 84:   KSPSetUpOnBlocks(ksp);
 85:   PetscGetTime(&tsetup2);
 86:   tsetup = tsetup2 -tsetup1;
 87:   PetscLogStagePop();
 88:   PetscBarrier((PetscObject)A);

 90:   PetscLogStageRegister("mystage 2",&stage2);
 91:   PetscLogStagePush(stage2);
 92:   PetscGetTime(&tsolve1);
 93:   KSPSolve(ksp,b,x);
 94:   PetscGetTime(&tsolve2);
 95:   tsolve = tsolve2 - tsolve1;
 96:   PetscLogStagePop();

 98:   /* Show result */
 99:   MatMult(A,x,u);
100:   VecAXPY(u,-1.0,b);
101:   VecNorm(u,NORM_2,&norm);
102:   KSPGetIterationNumber(ksp,&its);
103:   /*  matrix PC   KSP   Options       its    residual setuptime solvetime  */
104:   if (table) {
105:     char   *matrixname,kspinfo[120];
106:     PetscViewer viewer;
107:     PetscViewerStringOpen(PETSC_COMM_WORLD,kspinfo,120,&viewer);
108:     KSPView(ksp,viewer);
109:     PetscStrrchr(file,'/',&matrixname);
110:     PetscPrintf(PETSC_COMM_WORLD,"%-8.8s %3D %2.0e %2.1e %2.1e %2.1e %s \n",
111:                        matrixname,its,norm,tsetup+tsolve,tsetup,tsolve,kspinfo);
112:     PetscViewerDestroy(&viewer);
113:   } else {
114:     PetscPrintf(PETSC_COMM_WORLD,"Number of iterations = %3D\n",its);
115:     PetscPrintf(PETSC_COMM_WORLD,"Residual norm = %G\n",norm);
116:   }

118:   /* Cleanup */
119:   KSPDestroy(&ksp);
120:   VecDestroy(&x);
121:   VecDestroy(&b);
122:   VecDestroy(&u);
123:   MatDestroy(&A);

125:   PetscFinalize();
126: #endif
127:   return 0;
128: }