Actual source code: ex17.c

  1: /*$Id: ex17.c,v 1.21 2001/08/07 21:30:08 bsmith Exp $*/

  3: static char help[] = "Tests the use of MatSolveTranspose().\n\n";

 5:  #include petscmat.h

  9: int main(int argc,char **args)
 10: {
 11:   Mat          C,A;
 12:   int          i,j,m = 5,n = 5,I,J,ierr;
 13:   PetscScalar  v,five = 5.0,one = 1.0,mone = -1.0;
 14:   IS           isrow,row,col;
 15:   Vec          x,u,b;
 16:   PetscReal    norm;

 18:   PetscInitialize(&argc,&args,(char *)0,help);
 19:   PetscOptionsGetInt(PETSC_NULL,"-m",&m,PETSC_NULL);
 20:   PetscOptionsGetInt(PETSC_NULL,"-n",&n,PETSC_NULL);

 22:   MatCreateSeqAIJ(PETSC_COMM_SELF,m*n,m*n,5,PETSC_NULL,&C);

 24:   /* create the matrix for the five point stencil, YET AGAIN*/
 25:   for (i=0; i<m; i++) {
 26:     for (j=0; j<n; j++) {
 27:       v = -1.0;  I = j + n*i;
 28:       if (i>0)   {J = I - n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 29:       if (i<m-1) {J = I + n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 30:       if (j>0)   {J = I - 1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 31:       if (j<n-1) {J = I + 1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 32:       v = 4.0; MatSetValues(C,1,&I,1,&I,&v,INSERT_VALUES);
 33:     }
 34:   }
 35:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 36:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

 38:   ISCreateStride(PETSC_COMM_SELF,(m*n)/2,0,2,&isrow);
 39:   MatZeroRows(C,isrow,&five);

 41:   VecCreateSeq(PETSC_COMM_SELF,m*n,&u);
 42:   VecDuplicate(u,&x);
 43:   VecDuplicate(u,&b);
 44:   VecSet(&one,u);

 46:   MatMultTranspose(C,u,b);

 48:   /* Set default ordering to be Quotient Minimum Degree; also read
 49:      orderings from the options database */
 50:   MatGetOrdering(C,MATORDERING_QMD,&row,&col);

 52:   MatLUFactorSymbolic(C,row,col,PETSC_NULL,&A);
 53:   MatLUFactorNumeric(C,&A);
 54:   MatSolveTranspose(A,b,x);

 56:   ISView(row,PETSC_VIEWER_STDOUT_SELF);
 57:   VecAXPY(&mone,u,x);
 58:   VecNorm(x,NORM_2,&norm);
 59:   PetscPrintf(PETSC_COMM_SELF,"Norm of error %g\n",norm);

 61:   ISDestroy(row);
 62:   ISDestroy(col);
 63:   ISDestroy(isrow);
 64:   VecDestroy(u);
 65:   VecDestroy(x);
 66:   VecDestroy(b);
 67:   MatDestroy(C);
 68:   MatDestroy(A);
 69:   PetscFinalize();
 70:   return 0;
 71: }