Actual source code: ex15.c

  1: /*$Id: ex15.c,v 1.22 2001/08/07 21:30:08 bsmith Exp $*/

  3: static char help[] = "Tests MatNorm(), MatLUFactor(), MatSolve() and MatSolveAdd().\n\n";

 5:  #include petscmat.h

  9: int main(int argc,char **args)
 10: {
 11:   Mat         C;
 12:   int         i,j,m = 3,n = 3,I,J,ierr;
 13:   PetscTruth  flg;
 14:   PetscScalar v,mone = -1.0,one = 1.0,alpha = 2.0;
 15:   IS          perm,iperm;
 16:   Vec         x,u,b,y;
 17:   PetscReal   norm;
 18:   MatFactorInfo   info;

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

 22:   MatCreate(PETSC_COMM_WORLD,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n,&C);
 23:   MatSetFromOptions(C);
 24:   PetscOptionsHasName(PETSC_NULL,"-symmetric",&flg);
 25:   if (flg) {  /* Treat matrix as symmetric only if we set this flag */
 26:     MatSetOption(C,MAT_SYMMETRIC);
 27:     MatSetOption(C,MAT_SYMMETRY_ETERNAL);
 28:   }

 30:   /* Create the matrix for the five point stencil, YET AGAIN */
 31:   for (i=0; i<m; i++) {
 32:     for (j=0; j<n; j++) {
 33:       v = -1.0;  I = j + n*i;
 34:       if (i>0)   {J = I - n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 35:       if (i<m-1) {J = I + n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 36:       if (j>0)   {J = I - 1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 37:       if (j<n-1) {J = I + 1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 38:       v = 4.0; MatSetValues(C,1,&I,1,&I,&v,INSERT_VALUES);
 39:     }
 40:   }
 41:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 42:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
 43:   MatGetOrdering(C,MATORDERING_RCM,&perm,&iperm);
 44:   MatView(C,PETSC_VIEWER_STDOUT_WORLD);
 45:   ISView(perm,PETSC_VIEWER_STDOUT_SELF);
 46:   VecCreateSeq(PETSC_COMM_SELF,m*n,&u);
 47:   VecSet(&one,u);
 48:   VecDuplicate(u,&x);
 49:   VecDuplicate(u,&b);
 50:   VecDuplicate(u,&y);
 51:   MatMult(C,u,b);
 52:   VecCopy(b,y);
 53:   VecScale(&alpha,y);

 55:   MatNorm(C,NORM_FROBENIUS,&norm);
 56:   PetscPrintf(PETSC_COMM_SELF,"Frobenius norm of matrix %g\n",norm);
 57:   MatNorm(C,NORM_1,&norm);
 58:   PetscPrintf(PETSC_COMM_SELF,"One  norm of matrix %g\n",norm);
 59:   MatNorm(C,NORM_INFINITY,&norm);
 60:   PetscPrintf(PETSC_COMM_SELF,"Infinity norm of matrix %g\n",norm);

 62:   info.fill = 2.0;
 63:   info.dtcol = 0.0;
 64:   info.damping = 0.0;
 65:   info.zeropivot = 1.e-14;
 66:   info.pivotinblocks = 1.0;
 67:   MatLUFactor(C,perm,iperm,&info);
 68:   MatView(C,PETSC_VIEWER_STDOUT_WORLD);

 70:   /* Test MatSolve */
 71:   MatSolve(C,b,x);
 72:   VecView(b,PETSC_VIEWER_STDOUT_SELF);
 73:   VecView(x,PETSC_VIEWER_STDOUT_SELF);
 74:   VecAXPY(&mone,u,x);
 75:   VecNorm(x,NORM_2,&norm);
 76:   PetscPrintf(PETSC_COMM_SELF,"Norm of error %A\n",norm);

 78:   /* Test MatSolveAdd */
 79:   MatSolveAdd(C,b,y,x);
 80:   VecAXPY(&mone,y,x);
 81:   VecAXPY(&mone,u,x);
 82:   VecNorm(x,NORM_2,&norm);

 84:   PetscPrintf(PETSC_COMM_SELF,"Norm of error %A\n",norm);

 86:   ISDestroy(perm);
 87:   ISDestroy(iperm);
 88:   VecDestroy(u);
 89:   VecDestroy(y);
 90:   VecDestroy(b);
 91:   VecDestroy(x);
 92:   MatDestroy(C);
 93:   PetscFinalize();
 94:   return 0;
 95: }