Actual source code: ex150.c

  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>

  5: extern PetscErrorCode InputTransformFFT(Mat,Vec,Vec);
  6: extern PetscErrorCode OutputTransformFFT(Mat,Vec,Vec);
  7: int main(int argc,char **args)
  8: {
  9:   PetscMPIInt    rank,size;
 10:   PetscInt       N0=3,N1=3,N2=3,N3=3,N4=3,N=N0*N1*N2*N3;
 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;
 17:   PetscScalar    one=1;

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

 24:   MPI_Comm_size(PETSC_COMM_WORLD, &size);
 25:   MPI_Comm_rank(PETSC_COMM_WORLD, &rank);

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

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

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

 47:   InputTransformFFT(A,input,x);

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

 57:   OutputTransformFFT(A,z,output);

 59:   fac  = 1.0/(PetscReal)N;
 60:   VecScale(output,fac);

 62:   VecAssemblyBegin(input);
 63:   VecAssemblyEnd(input);
 64:   VecAssemblyBegin(output);
 65:   VecAssemblyEnd(output);

 67:   VecView(input,PETSC_VIEWER_STDOUT_WORLD);
 68:   VecView(output,PETSC_VIEWER_STDOUT_WORLD);

 70:   VecAXPY(output,-1.0,input);
 71:   VecNorm(output,NORM_1,&enorm);
 72: /*  if (enorm > 1.e-14) { */
 73:   if (rank == 0) {
 74:     PetscPrintf(PETSC_COMM_SELF,"  Error norm of |x - z| %e\n",enorm);
 75:   }
 76: /*      } */

 78: /* MatCreateVecs(A,&z,NULL); */
 79: /*  printf("Vector size from ex148 %d\n",vsize); */
 80: /*  PetscObjectSetName((PetscObject) x, "Real space vector"); */
 81: /*      PetscObjectSetName((PetscObject) y, "Frequency space vector"); */
 82: /*      PetscObjectSetName((PetscObject) z, "Reconstructed vector"); */

 84:   VecDestroy(&output);
 85:   VecDestroy(&input);
 86:   VecDestroy(&x);
 87:   VecDestroy(&y);
 88:   VecDestroy(&z);
 89:   MatDestroy(&A);
 90:   PetscRandomDestroy(&rdm);
 91:   PetscFinalize();
 92:   return 0;
 93: }