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

Actual source code: ex155.c
petsc-3.4.2 2013-07-02

      1: static char help[]="This program illustrates the use of PETSc-fftw interface for parallel real DFT\n";
      2: #include <petscmat.h>
      3: #include <fftw3-mpi.h>
      4: /*extern PetscErrorCode MatGetVecsFFT(Mat,Vec *,Vec *,Vec *);*/
      7: PetscInt main(PetscInt argc,char **args)
      8: {
     10:   PetscMPIInt    rank,size;
     11:   PetscInt       N0=4096,N1=4096,N2=256,N3=10,N4=10,N=N0*N1;
     12:   PetscRandom    rdm;
     13:   PetscReal      enorm;
     14:   Vec            x,y,z,input,output;
     15:   Mat            A;
     16:   PetscInt       DIM, dim[5],vsize,row,col;
     17:   PetscReal      fac;

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

     23: /*  if (size!=1) */
     24: /*    SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP, "This is a uni-processor example only"); */
     25: #if defined(PETSC_USE_COMPLEX)
     26:   SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP, "Example for Real DFT. Your current data type is complex!");
     27: #endif
     28:   PetscRandomCreate(PETSC_COMM_WORLD, &rdm);
     29:   PetscRandomSetFromOptions(rdm);
     30:   VecCreate(PETSC_COMM_WORLD,&input);
     31:   VecSetSizes(input,PETSC_DECIDE,N);
     32:   VecSetFromOptions(input);
     33:   VecSetRandom(input,rdm);
     34:   VecDuplicate(input,&output);

     36:   DIM  = 2; dim[0] = N0; dim[1] = N1; dim[2] = N2; dim[3] = N3; dim[4] = N4;
     37:   MatCreateFFT(PETSC_COMM_WORLD,DIM,dim,MATFFTW,&A);
     38:   MatGetLocalSize(A,&row,&col);
     39:   printf("The Matrix size  is %d and %d from process %d\n",row,col,rank);
     40:   MatGetVecsFFTW(A,&x,&y,&z);

     42:   VecGetSize(x,&vsize);

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

     47:   VecScatterPetscToFFTW(A,input,x);
     48:   /*VecDestroy(&input);*/
     49:   MatMult(A,x,y);
     50:   MatMultTranspose(A,y,z);
     51:   VecScatterFFTWToPetsc(A,z,output);
     52:   /*VecDestroy(&z);*/
     53:   fac  = 1.0/(PetscReal)N;
     54:   VecScale(output,fac);

     56:   VecAssemblyBegin(input);
     57:   VecAssemblyEnd(input);
     58:   VecAssemblyBegin(output);
     59:   VecAssemblyEnd(output);

     61: /*  VecView(input,PETSC_VIEWER_STDOUT_WORLD);*/
     62: /*  VecView(output,PETSC_VIEWER_STDOUT_WORLD);*/

     64:   VecAXPY(output,-1.0,input);
     65:   VecNorm(output,NORM_1,&enorm);
     66:   if (enorm > 1.e-14) {
     67:     PetscPrintf(PETSC_COMM_SELF,"  Error norm of |x - z| %e\n",enorm);
     68:   }

     70:   VecDestroy(&x);
     71:   VecDestroy(&y);
     72:   VecDestroy(&z);
     73:   VecDestroy(&output);
     74:   VecDestroy(&input);
     75:   MatDestroy(&A);
     76:   PetscRandomDestroy(&rdm);
     77:   PetscFinalize();
     78:   return 0;

     80: }