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 69371c9d4SSatish Balay int main(int argc, char **args) { 7c4762a1bSJed Brown PetscMPIInt rank, size; 8c4762a1bSJed Brown PetscInt N0 = 50, N1 = 50, N = N0 * N1; 9c4762a1bSJed Brown PetscRandom rdm; 10c4762a1bSJed Brown PetscReal enorm; 11c4762a1bSJed Brown Vec x, y, z, input, output; 12c4762a1bSJed Brown Mat A; 13c4762a1bSJed Brown PetscInt DIM, dim[2]; 14c4762a1bSJed Brown PetscReal fac; 15c4762a1bSJed Brown 16327415f7SBarry Smith PetscFunctionBeginUser; 179566063dSJacob Faibussowitsch PetscCall(PetscInitialize(&argc, &args, (char *)0, help)); 18c4762a1bSJed Brown #if defined(PETSC_USE_COMPLEX) 19c4762a1bSJed Brown SETERRQ(PETSC_COMM_WORLD, PETSC_ERR_SUP, "This example requires real numbers"); 20c4762a1bSJed Brown #endif 21c4762a1bSJed Brown 229566063dSJacob Faibussowitsch PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size)); 239566063dSJacob Faibussowitsch PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank)); 24c4762a1bSJed Brown 25c4762a1bSJed Brown /* Create and set PETSc vectors 'input' and 'output' */ 269566063dSJacob Faibussowitsch PetscCall(PetscRandomCreate(PETSC_COMM_WORLD, &rdm)); 279566063dSJacob Faibussowitsch PetscCall(PetscRandomSetFromOptions(rdm)); 28c4762a1bSJed Brown 299566063dSJacob Faibussowitsch PetscCall(VecCreate(PETSC_COMM_WORLD, &input)); 309566063dSJacob Faibussowitsch PetscCall(VecSetSizes(input, PETSC_DECIDE, N0 * N1)); 319566063dSJacob Faibussowitsch PetscCall(VecSetFromOptions(input)); 329566063dSJacob Faibussowitsch PetscCall(VecSetRandom(input, rdm)); 339566063dSJacob Faibussowitsch PetscCall(VecDuplicate(input, &output)); 349566063dSJacob Faibussowitsch PetscCall(PetscObjectSetName((PetscObject)input, "Real space vector")); 359566063dSJacob Faibussowitsch PetscCall(PetscObjectSetName((PetscObject)output, "Reconstructed vector")); 36c4762a1bSJed Brown 37c4762a1bSJed Brown /* Get FFTW vectors 'x', 'y' and 'z' */ 38c4762a1bSJed Brown DIM = 2; 399371c9d4SSatish Balay dim[0] = N0; 409371c9d4SSatish Balay 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)); 61*48a46eb9SPierre Jolivet if (enorm > 1.e-11 && rank == 0) PetscCall(PetscPrintf(PETSC_COMM_SELF, " Error norm of |x - z| %e\n", enorm)); 62c4762a1bSJed Brown 63c4762a1bSJed Brown /* Free spaces */ 649566063dSJacob Faibussowitsch PetscCall(PetscRandomDestroy(&rdm)); 659566063dSJacob Faibussowitsch PetscCall(VecDestroy(&input)); 669566063dSJacob Faibussowitsch PetscCall(VecDestroy(&output)); 679566063dSJacob Faibussowitsch PetscCall(VecDestroy(&x)); 689566063dSJacob Faibussowitsch PetscCall(VecDestroy(&y)); 699566063dSJacob Faibussowitsch PetscCall(VecDestroy(&z)); 709566063dSJacob Faibussowitsch PetscCall(MatDestroy(&A)); 71c4762a1bSJed Brown 729566063dSJacob Faibussowitsch PetscCall(PetscFinalize()); 73b122ec5aSJacob Faibussowitsch return 0; 74c4762a1bSJed Brown } 75c4762a1bSJed Brown 76c4762a1bSJed Brown /*TEST 77c4762a1bSJed Brown 78c4762a1bSJed Brown build: 79c4762a1bSJed Brown requires: fftw !complex 80c4762a1bSJed Brown 81c4762a1bSJed Brown test: 82c4762a1bSJed Brown output_file: output/ex148.out 83c4762a1bSJed Brown 84c4762a1bSJed Brown test: 85c4762a1bSJed Brown suffix: 2 86c4762a1bSJed Brown nsize: 3 87c4762a1bSJed Brown output_file: output/ex148.out 88c4762a1bSJed Brown 89c4762a1bSJed Brown TEST*/ 90