1c4762a1bSJed Brown static char help[]="This program illustrates the use of PETSc-fftw interface for real 2D DFT.\n\ 2c4762a1bSJed Brown See ~petsc/src/mat/tests/ex158.c for general cases. \n\n"; 3c4762a1bSJed Brown 4c4762a1bSJed Brown #include <petscmat.h> 5c4762a1bSJed Brown 6c4762a1bSJed Brown int main(int argc,char **args) 7c4762a1bSJed Brown { 8c4762a1bSJed Brown PetscMPIInt rank,size; 9c4762a1bSJed Brown PetscInt N0=50,N1=50,N=N0*N1; 10c4762a1bSJed Brown PetscRandom rdm; 11c4762a1bSJed Brown PetscReal enorm; 12c4762a1bSJed Brown Vec x,y,z,input,output; 13c4762a1bSJed Brown Mat A; 14c4762a1bSJed Brown PetscInt DIM,dim[2]; 15c4762a1bSJed Brown PetscReal fac; 16c4762a1bSJed Brown 17*327415f7SBarry Smith PetscFunctionBeginUser; 189566063dSJacob Faibussowitsch PetscCall(PetscInitialize(&argc,&args,(char*)0,help)); 19c4762a1bSJed Brown #if defined(PETSC_USE_COMPLEX) 20c4762a1bSJed Brown SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP, "This example requires real numbers"); 21c4762a1bSJed Brown #endif 22c4762a1bSJed Brown 239566063dSJacob Faibussowitsch PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size)); 249566063dSJacob Faibussowitsch PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank)); 25c4762a1bSJed Brown 26c4762a1bSJed Brown /* Create and set PETSc vectors 'input' and 'output' */ 279566063dSJacob Faibussowitsch PetscCall(PetscRandomCreate(PETSC_COMM_WORLD, &rdm)); 289566063dSJacob Faibussowitsch PetscCall(PetscRandomSetFromOptions(rdm)); 29c4762a1bSJed Brown 309566063dSJacob Faibussowitsch PetscCall(VecCreate(PETSC_COMM_WORLD,&input)); 319566063dSJacob Faibussowitsch PetscCall(VecSetSizes(input,PETSC_DECIDE,N0*N1)); 329566063dSJacob Faibussowitsch PetscCall(VecSetFromOptions(input)); 339566063dSJacob Faibussowitsch PetscCall(VecSetRandom(input,rdm)); 349566063dSJacob Faibussowitsch PetscCall(VecDuplicate(input,&output)); 359566063dSJacob Faibussowitsch PetscCall(PetscObjectSetName((PetscObject)input, "Real space vector")); 369566063dSJacob Faibussowitsch PetscCall(PetscObjectSetName((PetscObject)output, "Reconstructed vector")); 37c4762a1bSJed Brown 38c4762a1bSJed Brown /* Get FFTW vectors 'x', 'y' and 'z' */ 39c4762a1bSJed Brown DIM = 2; 40c4762a1bSJed Brown dim[0] = N0; dim[1] = N1; 419566063dSJacob Faibussowitsch PetscCall(MatCreateFFT(PETSC_COMM_WORLD,DIM,dim,MATFFTW,&A)); 429566063dSJacob Faibussowitsch PetscCall(MatCreateVecsFFTW(A,&x,&y,&z)); 43c4762a1bSJed Brown 44c4762a1bSJed Brown /* Scatter PETSc vector 'input' to FFTW vector 'x' */ 459566063dSJacob Faibussowitsch PetscCall(VecScatterPetscToFFTW(A,input,x)); 46c4762a1bSJed Brown 47c4762a1bSJed Brown /* Apply forward FFT */ 489566063dSJacob Faibussowitsch PetscCall(MatMult(A,x,y)); 49c4762a1bSJed Brown 50c4762a1bSJed Brown /* Apply backward FFT */ 519566063dSJacob Faibussowitsch PetscCall(MatMultTranspose(A,y,z)); 52c4762a1bSJed Brown 53c4762a1bSJed Brown /* Scatter FFTW vector 'z' to PETSc vector 'output' */ 549566063dSJacob Faibussowitsch PetscCall(VecScatterFFTWToPetsc(A,z,output)); 55c4762a1bSJed Brown 56c4762a1bSJed Brown /* Check accuracy */ 57c4762a1bSJed Brown fac = 1.0/(PetscReal)N; 589566063dSJacob Faibussowitsch PetscCall(VecScale(output,fac)); 599566063dSJacob Faibussowitsch PetscCall(VecAXPY(output,-1.0,input)); 609566063dSJacob Faibussowitsch PetscCall(VecNorm(output,NORM_1,&enorm)); 61dd400576SPatrick Sanan if (enorm > 1.e-11 && rank == 0) { 629566063dSJacob Faibussowitsch PetscCall(PetscPrintf(PETSC_COMM_SELF," Error norm of |x - z| %e\n",enorm)); 63c4762a1bSJed Brown } 64c4762a1bSJed Brown 65c4762a1bSJed Brown /* Free spaces */ 669566063dSJacob Faibussowitsch PetscCall(PetscRandomDestroy(&rdm)); 679566063dSJacob Faibussowitsch PetscCall(VecDestroy(&input)); 689566063dSJacob Faibussowitsch PetscCall(VecDestroy(&output)); 699566063dSJacob Faibussowitsch PetscCall(VecDestroy(&x)); 709566063dSJacob Faibussowitsch PetscCall(VecDestroy(&y)); 719566063dSJacob Faibussowitsch PetscCall(VecDestroy(&z)); 729566063dSJacob Faibussowitsch PetscCall(MatDestroy(&A)); 73c4762a1bSJed Brown 749566063dSJacob Faibussowitsch PetscCall(PetscFinalize()); 75b122ec5aSJacob Faibussowitsch return 0; 76c4762a1bSJed Brown } 77c4762a1bSJed Brown 78c4762a1bSJed Brown /*TEST 79c4762a1bSJed Brown 80c4762a1bSJed Brown build: 81c4762a1bSJed Brown requires: fftw !complex 82c4762a1bSJed Brown 83c4762a1bSJed Brown test: 84c4762a1bSJed Brown output_file: output/ex148.out 85c4762a1bSJed Brown 86c4762a1bSJed Brown test: 87c4762a1bSJed Brown suffix: 2 88c4762a1bSJed Brown nsize: 3 89c4762a1bSJed Brown output_file: output/ex148.out 90c4762a1bSJed Brown 91c4762a1bSJed Brown TEST*/ 92