Actual source code: ex9.c

petsc-3.5.4 2015-05-23
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  1: 
  2: static char help[] = "Tests MPI parallel matrix creation. Test MatGetRedundantMatrix() \n\n";

  4: #include <petscmat.h>

  8: int main(int argc,char **args)
  9: {
 10:   Mat            C;
 11:   MatInfo        info;
 12:   PetscMPIInt    rank,size;
 13:   PetscInt       i,j,m = 3,n = 2,low,high,iglobal;
 14:   PetscInt       Ii,J,ldim;
 16:   PetscBool      flg_info,flg_mat;
 17:   PetscScalar    v,one = 1.0;
 18:   Vec            x,y;

 20:   PetscInitialize(&argc,&args,(char*)0,help);
 21:   PetscOptionsGetInt(NULL,"-m",&m,NULL);
 22:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
 23:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 24:   n    = 2*size;

 26:   MatCreate(PETSC_COMM_WORLD,&C);
 27:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n);
 28:   MatSetFromOptions(C);
 29:   MatSetUp(C);

 31:   /* Create the matrix for the five point stencil, YET AGAIN */
 32:   for (i=0; i<m; i++) {
 33:     for (j=2*rank; j<2*rank+2; j++) {
 34:       v = -1.0;  Ii = j + n*i;
 35:       if (i>0)   {J = Ii - n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 36:       if (i<m-1) {J = Ii + n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 37:       if (j>0)   {J = Ii - 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 38:       if (j<n-1) {J = Ii + 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 39:       v = 4.0; MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES);
 40:     }
 41:   }

 43:   /* Add extra elements (to illustrate variants of MatGetInfo) */
 44:   Ii   = n; J = n-2; v = 100.0;
 45:   MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);
 46:   Ii   = n-2; J = n; v = 100.0;
 47:   MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);

 49:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 50:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

 52:   /* Form vectors */
 53:   MatGetVecs(C,&x,&y);
 54:   VecGetLocalSize(x,&ldim);
 55:   VecGetOwnershipRange(x,&low,&high);
 56:   for (i=0; i<ldim; i++) {
 57:     iglobal = i + low;
 58:     v       = one*((PetscReal)i) + 100.0*rank;
 59:     VecSetValues(x,1,&iglobal,&v,INSERT_VALUES);
 60:   }
 61:   VecAssemblyBegin(x);
 62:   VecAssemblyEnd(x);

 64:   MatMult(C,x,y);
 65:   /*
 66:   VecView(x,PETSC_VIEWER_STDOUT_WORLD);
 67:   VecView(y,PETSC_VIEWER_STDOUT_WORLD);
 68:    */
 69:   PetscOptionsHasName(NULL,"-view_info",&flg_info);
 70:   if (flg_info)  {
 71:     PetscViewerSetFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO);
 72:     MatView(C,PETSC_VIEWER_STDOUT_WORLD);
 73: 
 74:     MatGetInfo(C,MAT_GLOBAL_SUM,&info);
 75:     PetscPrintf(PETSC_COMM_WORLD,"matrix information (global sums):\n\
 76:      nonzeros = %D, allocated nonzeros = %D\n",(PetscInt)info.nz_used,(PetscInt)info.nz_allocated);
 77:     MatGetInfo (C,MAT_GLOBAL_MAX,&info);
 78:     PetscPrintf(PETSC_COMM_WORLD,"matrix information (global max):\n\
 79:      nonzeros = %D, allocated nonzeros = %D\n",(PetscInt)info.nz_used,(PetscInt)info.nz_allocated);
 80:   }
 81: 
 82:   PetscOptionsHasName(NULL,"-view_mat",&flg_mat);
 83:   if (flg_mat) {
 84:     MatView(C,PETSC_VIEWER_STDOUT_WORLD);
 85:   }

 87:   /* Test MatGetRedundantMatrix() */
 88:   if (size > 1) {
 89:     MPI_Comm       subcomm;
 90:     Mat            Credundant;
 91:     PetscInt       Nsubcomms = size;
 92:     PetscMPIInt    nsubcomms,subsize;

 94:     PetscOptionsGetInt(NULL,"-nsubcomms",&Nsubcomms,NULL);
 95:     PetscMPIIntCast(Nsubcomms,&nsubcomms);
 96:     if (nsubcomms > size) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"nsubcomms %d cannot > ncomms %d",nsubcomms,size);

 98:     MatGetRedundantMatrix(C,nsubcomms,MPI_COMM_NULL,MAT_INITIAL_MATRIX,&Credundant);
 99:     MatGetRedundantMatrix(C,nsubcomms,MPI_COMM_NULL,MAT_REUSE_MATRIX,&Credundant);

101:     PetscObjectGetComm((PetscObject)Credundant,&subcomm);
102:     MPI_Comm_size(subcomm,&subsize);
103: 
104:     if (subsize==1 && flg_mat) {
105:       printf("\n[%d] Credundant:\n",rank);
106:      MatView(Credundant,PETSC_VIEWER_STDOUT_SELF);
107:     }
108:     MatDestroy(&Credundant);
109:   }

111:   VecDestroy(&x);
112:   VecDestroy(&y);
113:   MatDestroy(&C);
114:   PetscFinalize();
115:   return 0;
116: }