Date: 2013-07-02T14:44:23+00:00

Actual source code: ex153.c
petsc-3.4.2 2013-07-02

      1: static char help[]="This program illustrates the use of PETSc-fftw interface for sequential real DFT\n";
      2: #include <petscmat.h>
      3: #include <fftw3-mpi.h>
      6: PetscInt main(PetscInt argc,char **args)
      7: {
      9:   PetscMPIInt    rank,size;
     10:   PetscInt       N0=10,N1=10,N2=10,N3=10,N4=10,N=N0*N1*N2*N3*N4;
     11:   PetscRandom    rdm;
     12:   PetscReal      enorm;
     13:   Vec            x,y,z,input,output;
     14:   Mat            A;
     15:   PetscInt       DIM, dim[5],vsize;
     16:   PetscReal      fac;

     18:   PetscInitialize(&argc,&args,(char*)0,help);
     19:   MPI_Comm_size(PETSC_COMM_WORLD, &size);
     20:   MPI_Comm_rank(PETSC_COMM_WORLD, &rank);

     22:   if (size!=1) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP, "This is a uni-processor example only");
     23:   PetscRandomCreate(PETSC_COMM_SELF, &rdm);
     24:   PetscRandomSetFromOptions(rdm);
     25:   VecCreate(PETSC_COMM_SELF,&input);
     26:   VecSetSizes(input,N,N);
     27:   VecSetFromOptions(input);
     28:   VecSetRandom(input,rdm);
     29:   VecDuplicate(input,&output);

     31:   DIM  = 5; dim[0] = N0; dim[1] = N1; dim[2] = N2; dim[3] = N3; dim[4] = N4;
     32:   MatCreateFFT(PETSC_COMM_SELF,DIM,dim,MATFFTW,&A);
     33:   MatGetVecs(A,&x,&y);
     34:   MatGetVecs(A,&z,NULL);

     36:   VecGetSize(x,&vsize);
     37:   printf("The vector size  of input from the main routine is %d\n",vsize);

     39:   VecGetSize(z,&vsize);
     40:   printf("The vector size of output from the main routine is %d\n",vsize);

     42:   InputTransformFFT(A,input,x);

     44:   MatMult(A,x,y);
     45:   MatMultTranspose(A,y,z);

     47:   OutputTransformFFT(A,z,output);
     48:   fac  = 1.0/(PetscReal)N;
     49:   VecScale(output,fac);
     50: /*
     51:   VecAssemblyBegin(input);
     52:   VecAssemblyEnd(input);
     53:   VecAssemblyBegin(output);
     54:   VecAssemblyEnd(output);

     56:   VecView(input,PETSC_VIEWER_STDOUT_WORLD);
     57:   VecView(output,PETSC_VIEWER_STDOUT_WORLD);
     58: */
     59:   VecAXPY(output,-1.0,input);
     60:   VecNorm(output,NORM_1,&enorm);
     61: /*  if (enorm > 1.e-14) { */
     62:   PetscPrintf(PETSC_COMM_SELF,"  Error norm of |x - z| %e\n",enorm);
     63: /*      } */

     65:   VecDestroy(&output);
     66:   VecDestroy(&input);
     67:   VecDestroy(&x);
     68:   VecDestroy(&y);
     69:   VecDestroy(&z);
     70:   MatDestroy(&A);
     71:   PetscRandomDestroy(&rdm);
     72:   PetscFinalize();
     73:   return 0;

     75: }