Actual source code: ex25.c

  1: /*$Id: ex25.c,v 1.3 2000/11/15 22:56:05 balay Exp $*/

  3: static char help[] =
  4: "Tests CG, MINRES and SYMMLQ on the symmetric indefinite matrices: afiro and golan\n\
  5: Runtime options: ex25 -fload ~petsc/matrices/indefinite/afiro -pc_type jacobi -pc_jacobi_rowmax\n\
  6: See ~petsc/matrices/indefinite/readme \n\n";

 8:  #include petscksp.h

 12: int main(int argc,char **args)
 13: {
 14:   Mat         C;
 15:   PetscScalar      v,none = -1.0;
 16:   int         i,j,ierr,Istart,Iend,N,rank,size,its,k;
 17:   double      err_norm,res_norm;
 18:   Vec         x,b,u,u_tmp;
 19:   PetscRandom r;
 20:   PC          pc;
 21:   KSP         ksp;
 22:   PetscViewer      view;
 23:   char        filein[128];     /* input file name */

 25:   PetscInitialize(&argc,&args,(char *)0,help);
 26:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
 27:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 28: 
 29:   /* Load the binary data file "filein". Set runtime option: -fload filein */
 30:   PetscPrintf(PETSC_COMM_WORLD,"\n Load dataset ...\n");
 31:   PetscOptionsGetString(PETSC_NULL,"-fload",filein,127,PETSC_NULL);
 32:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,filein,FILE_MODE_READ,&view);
 33:   MatLoad(view,MATMPISBAIJ,&C);
 34:   VecLoad(view,VECMPI,&b);
 35:   VecLoad(view,VECMPI,&u);
 36:   PetscViewerDestroy(view);
 37:   /* VecView(b,VIEWER_STDOUT_WORLD); */
 38:   /* MatView(C,VIEWER_STDOUT_WORLD); */

 40:   VecDuplicate(u,&u_tmp);

 42:   /* Check accuracy of the data */
 43:   /*
 44:   MatMult(C,u,u_tmp);
 45:   VecAXPY(u_tmp,none,b);
 46:   VecNorm(u_tmp,NORM_2,&res_norm);
 47:   PetscPrintf(PETSC_COMM_WORLD,"Accuracy of the loading data: | b - A*u |_2 : %A \n",res_norm); 
 48:   */

 50:   /* Setup and solve for system */
 51:   VecDuplicate(b,&x);
 52:   for (k=0; k<3; k++){
 53:     if (k == 0){                              /* CG  */
 54:       KSPCreate(PETSC_COMM_WORLD,&ksp);
 55:       KSPSetType(ksp,KSPCG);
 56:       KSPSetOperators(ksp,C,C,DIFFERENT_NONZERO_PATTERN);
 57:       PetscPrintf(PETSC_COMM_WORLD,"\n CG: \n");
 58:     } else if (k == 1){                       /* MINRES */
 59:       KSPCreate(PETSC_COMM_WORLD,&ksp);
 60:       KSPSetType(ksp,KSPMINRES);
 61:       KSPSetOperators(ksp,C,C,DIFFERENT_NONZERO_PATTERN);
 62:       PetscPrintf(PETSC_COMM_WORLD,"\n MINRES: \n");
 63:     } else {                                 /* SYMMLQ */
 64:       KSPCreate(PETSC_COMM_WORLD,&ksp);
 65:       KSPSetOperators(ksp,C,C,DIFFERENT_NONZERO_PATTERN);
 66:       KSPSetType(ksp,KSPSYMMLQ);
 67:       PetscPrintf(PETSC_COMM_WORLD,"\n SYMMLQ: \n");
 68:     }

 70:     KSPGetPC(ksp,&pc);
 71:     PCSetType(pc,PCNONE);
 72:     /* PCSetType(pc,PCJACOBI); */
 73:     KSPSetTolerances(ksp,1.e-7,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);

 75:     /*
 76:     Set runtime options, e.g.,
 77:         -ksp_type <type> -pc_type <type> -ksp_monitor -ksp_rtol <rtol>
 78:                          -pc_type jacobi -pc_jacobi_rowmax
 79:     These options will override those specified above as long as
 80:     KSPSetFromOptions() is called _after_ any other customization routines.
 81:     */
 82:     KSPSetFromOptions(ksp);

 84:     /* Solve linear system; */
 85:     KSPSolve(ksp,b,x);
 86:     KSPGetIterationNumber(ksp,&its);
 87: 
 88:   /* Check error */
 89:     VecCopy(u,u_tmp);
 90:     VecAXPY(u_tmp,none,x);
 91:     VecNorm(u_tmp,NORM_2,&err_norm);
 92:     MatMult(C,x,u_tmp);
 93:     VecAXPY(u_tmp,none,b);
 94:     VecNorm(u_tmp,NORM_2,&res_norm);
 95: 
 96:     PetscPrintf(PETSC_COMM_WORLD,"Number of iterations = %3d\n",its);
 97:     PetscPrintf(PETSC_COMM_WORLD,"Residual norm: %A;",res_norm);
 98:     PetscPrintf(PETSC_COMM_WORLD,"  Error norm: %A.\n",err_norm);

100:     KSPDestroy(ksp);
101:   }
102: 
103:   /* 
104:        Free work space.  All PETSc objects should be destroyed when they
105:        are no longer needed.
106:   */
107:   VecDestroy(b);
108:   VecDestroy(u);
109:   VecDestroy(x);
110:   VecDestroy(u_tmp);
111:   MatDestroy(C);

113:   PetscFinalize();
114:   return 0;
115: }