Actual source code: ex6.c

  1: /*$Id: ex6.c,v 1.74 2001/09/11 16:33:24 bsmith Exp $*/

  3: static char help[] = "Reads a PETSc matrix and vector from a file and solves a linear system.n
  4: Input arguments are:n
  5:   -f <input_file> : file to load.  For a 5X5 example of the 5-pt. stencil,n
  6:                     use the file petsc/src/mat/examples/matbinary.exnn";

 8:  #include petscsles.h
 9:  #include petsclog.h

 11: int main(int argc,char **args)
 12: {
 13: #if !defined(PETSC_USE_COMPLEX)
 14:   int            ierr,its,stage1,stage2;
 15:   PetscReal      norm;
 16:   PetscLogDouble tsetup1,tsetup2,tsetup,tsolve1,tsolve2,tsolve;
 17:   PetscScalar    zero = 0.0,none = -1.0;
 18:   Vec            x,b,u;
 19:   Mat            A;
 20:   SLES           sles;
 21:   char           file[128];
 22:   PetscViewer    fd;
 23:   PetscTruth     table,flg;
 24: #endif

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

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


 34:   /* Read matrix and RHS */
 35:   PetscOptionsGetString(PETSC_NULL,"-f",file,127,&flg);
 36:   if (!flg) SETERRQ(1,"Must indicate binary file with the -f option");
 37:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,file,PETSC_BINARY_RDONLY,&fd);

 39:   MatLoad(fd,MATSEQAIJ,&A);
 40:   VecLoad(fd,&b);
 41:   PetscViewerDestroy(fd);

 43:   /* 
 44:    If the load matrix is larger then the vector, due to being padded 
 45:    to match the blocksize then create a new padded vector
 46:   */
 47:   {
 48:     int    m,n,j,mvec,start,end,index;
 49:     Vec    tmp;
 50:     PetscScalar *bold;

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

 72:   VecSet(&zero,x);
 73:   PetscBarrier((PetscObject)A);

 75:   PetscLogStageRegister(&stage1,"mystage 1");
 76:   PetscLogStagePush(stage1);
 77:   PetscGetTime(&tsetup1);
 78:   SLESCreate(PETSC_COMM_WORLD,&sles);
 79:   SLESSetOperators(sles,A,A,DIFFERENT_NONZERO_PATTERN);
 80:   SLESSetFromOptions(sles);
 81:   SLESSetUp(sles,b,x);
 82:   SLESSetUpOnBlocks(sles);
 83:   PetscGetTime(&tsetup2);
 84:   tsetup = tsetup2 -tsetup1;
 85:   PetscLogStagePop();
 86:   PetscBarrier((PetscObject)A);

 88:   PetscLogStageRegister(&stage2,"mystage 2");
 89:   PetscLogStagePush(stage2);
 90:   PetscGetTime(&tsolve1);
 91:   SLESSolve(sles,b,x,&its);
 92:   PetscGetTime(&tsolve2);
 93:   tsolve = tsolve2 - tsolve1;
 94:   PetscLogStagePop();

 96:   /* Show result */
 97:   MatMult(A,x,u);
 98:   VecAXPY(&none,b,u);
 99:   VecNorm(u,NORM_2,&norm);
100:   /*  matrix PC   KSP   Options       its    residual setuptime solvetime  */
101:   if (table) {
102:     char   *matrixname,slesinfo[120];
103:     PetscViewer viewer;
104:     PetscViewerStringOpen(PETSC_COMM_WORLD,slesinfo,120,&viewer);
105:     SLESView(sles,viewer);
106:     PetscStrrchr(file,'/',&matrixname);
107:     PetscPrintf(PETSC_COMM_WORLD,"%-8.8s %3d %2.0e %2.1e %2.1e %2.1e %s n",
108:                        matrixname,its,norm,tsetup+tsolve,tsetup,tsolve,slesinfo);
109:     PetscViewerDestroy(viewer);
110:   } else {
111:     PetscPrintf(PETSC_COMM_WORLD,"Number of iterations = %3dn",its);
112:     PetscPrintf(PETSC_COMM_WORLD,"Residual norm = %An",norm);
113:   }

115:   /* Cleanup */
116:   SLESDestroy(sles);
117:   VecDestroy(x);
118:   VecDestroy(b);
119:   VecDestroy(u);
120:   MatDestroy(A);

122:   PetscFinalize();
123: #endif
124:   return 0;
125: }