Actual source code: ex150.c
petsc-3.4.2 2013-07-02

      1: static char help[]="This program illustrates the use of PETSc-fftw interface for real DFT\n";
      2: #include <petscmat.h>
      3: #include <fftw3-mpi.h>

      7: extern PetscErrorCode InputTransformFFT(Mat,Vec,Vec);
      8: extern PetscErrorCode OutputTransformFFT(Mat,Vec,Vec);
      9: PetscInt main(PetscInt argc,char **args)
     10: {
     12:   PetscMPIInt    rank,size;
     13:   PetscInt       N0=3,N1=3,N2=3,N3=3,N4=3,N=N0*N1*N2*N3;
     14:   PetscRandom    rdm;
     15:   PetscReal      enorm;
     16:   Vec            x,y,z,input,output;
     17:   Mat            A;
     18:   PetscInt       DIM, dim[5],vsize;
     19:   PetscReal      fac;
     20:   PetscScalar    one=1;

     22:   PetscInitialize(&argc,&args,(char*)0,help);
     23: #if defined(PETSC_USE_COMPLEX)
     24:   SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP, "This example requires real numbers");
     25: #endif

     27:   MPI_Comm_size(PETSC_COMM_WORLD, &size);
     28:   MPI_Comm_rank(PETSC_COMM_WORLD, &rank);

     30:   PetscRandomCreate(PETSC_COMM_WORLD, &rdm);
     31:   PetscRandomSetFromOptions(rdm);
     32:   VecCreate(PETSC_COMM_WORLD,&input);
     33:   VecSetSizes(input,PETSC_DECIDE,N);
     34:   VecSetFromOptions(input);
     35:   VecSetRandom(input,rdm);
     36:   VecAssemblyBegin(input);
     37:   VecAssemblyEnd(input);
     38: /*  VecView(input,PETSC_VIEWER_STDOUT_WORLD); */
     39:   VecDuplicate(input,&output);

     41:   DIM    = 4;
     42:   dim[0] = N0; dim[1] = N1; dim[2] = N2; dim[3] = N3; dim[4] = N4;

     44:   MatCreateFFT(PETSC_COMM_WORLD,DIM,dim,MATFFTW,&A);
     45:   MatGetVecs(A,&x,&y);
     46:   MatGetVecs(A,&z,NULL);
     47:   VecGetSize(x,&vsize);
     48:   printf("The vector size from the main routine is %d\n",vsize);

     50:   InputTransformFFT(A,input,x);

     52:   MatMult(A,x,y);
     53:   VecAssemblyBegin(y);
     54:   VecAssemblyEnd(y);
     55:   VecView(y,PETSC_VIEWER_STDOUT_WORLD);
     56:   MatMultTranspose(A,y,z);
     57:   VecGetSize(z,&vsize);
     58:   printf("The vector size of zfrom the main routine is %d\n",vsize);

     60:   OutputTransformFFT(A,z,output);

     62:   fac  = 1.0/(PetscReal)N;
     63:   VecScale(output,fac);

     65:   VecAssemblyBegin(input);
     66:   VecAssemblyEnd(input);
     67:   VecAssemblyBegin(output);
     68:   VecAssemblyEnd(output);

     70:   VecView(input,PETSC_VIEWER_STDOUT_WORLD);
     71:   VecView(output,PETSC_VIEWER_STDOUT_WORLD);

     73:   VecAXPY(output,-1.0,input);
     74:   VecNorm(output,NORM_1,&enorm);
     75: /*  if (enorm > 1.e-14) { */
     76:   if (!rank) {
     77:     PetscPrintf(PETSC_COMM_SELF,"  Error norm of |x - z| %e\n",enorm);
     78:   }
     79: /*      } */

     84: /* MatGetVecs(A,&z,NULL); */
     85: /*  printf("Vector size from ex148 %d\n",vsize); */
     86: /*  PetscObjectSetName((PetscObject) x, "Real space vector"); */
     87: /*      PetscObjectSetName((PetscObject) y, "Frequency space vector"); */
     88: /*      PetscObjectSetName((PetscObject) z, "Reconstructed vector"); */

     90:   VecDestroy(&output);
     91:   VecDestroy(&input);
     92:   VecDestroy(&x);
     93:   VecDestroy(&y);
     94:   VecDestroy(&z);
     95:   MatDestroy(&A);
     96:   PetscRandomDestroy(&rdm);
     97:   PetscFinalize();
     98:   return 0;
     99: }