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 PetscErrorCode ierr; 9c4762a1bSJed Brown PetscMPIInt rank,size; 10c4762a1bSJed Brown PetscInt N0=50,N1=50,N=N0*N1; 11c4762a1bSJed Brown PetscRandom rdm; 12c4762a1bSJed Brown PetscReal enorm; 13c4762a1bSJed Brown Vec x,y,z,input,output; 14c4762a1bSJed Brown Mat A; 15c4762a1bSJed Brown PetscInt DIM,dim[2]; 16c4762a1bSJed Brown PetscReal fac; 17c4762a1bSJed Brown 18c4762a1bSJed Brown ierr = PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr; 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 23*5f80ce2aSJacob Faibussowitsch CHKERRMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size)); 24*5f80ce2aSJacob Faibussowitsch CHKERRMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank)); 25c4762a1bSJed Brown 26c4762a1bSJed Brown /* Create and set PETSc vectors 'input' and 'output' */ 27*5f80ce2aSJacob Faibussowitsch CHKERRQ(PetscRandomCreate(PETSC_COMM_WORLD, &rdm)); 28*5f80ce2aSJacob Faibussowitsch CHKERRQ(PetscRandomSetFromOptions(rdm)); 29c4762a1bSJed Brown 30*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecCreate(PETSC_COMM_WORLD,&input)); 31*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecSetSizes(input,PETSC_DECIDE,N0*N1)); 32*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecSetFromOptions(input)); 33*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecSetRandom(input,rdm)); 34*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecDuplicate(input,&output)); 35*5f80ce2aSJacob Faibussowitsch CHKERRQ(PetscObjectSetName((PetscObject)input, "Real space vector")); 36*5f80ce2aSJacob Faibussowitsch CHKERRQ(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; 41*5f80ce2aSJacob Faibussowitsch CHKERRQ(MatCreateFFT(PETSC_COMM_WORLD,DIM,dim,MATFFTW,&A)); 42*5f80ce2aSJacob Faibussowitsch CHKERRQ(MatCreateVecsFFTW(A,&x,&y,&z)); 43c4762a1bSJed Brown 44c4762a1bSJed Brown /* Scatter PETSc vector 'input' to FFTW vector 'x' */ 45*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecScatterPetscToFFTW(A,input,x)); 46c4762a1bSJed Brown 47c4762a1bSJed Brown /* Apply forward FFT */ 48*5f80ce2aSJacob Faibussowitsch CHKERRQ(MatMult(A,x,y)); 49c4762a1bSJed Brown 50c4762a1bSJed Brown /* Apply backward FFT */ 51*5f80ce2aSJacob Faibussowitsch CHKERRQ(MatMultTranspose(A,y,z)); 52c4762a1bSJed Brown 53c4762a1bSJed Brown /* Scatter FFTW vector 'z' to PETSc vector 'output' */ 54*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecScatterFFTWToPetsc(A,z,output)); 55c4762a1bSJed Brown 56c4762a1bSJed Brown /* Check accuracy */ 57c4762a1bSJed Brown fac = 1.0/(PetscReal)N; 58*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecScale(output,fac)); 59*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecAXPY(output,-1.0,input)); 60*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecNorm(output,NORM_1,&enorm)); 61dd400576SPatrick Sanan if (enorm > 1.e-11 && rank == 0) { 62*5f80ce2aSJacob Faibussowitsch CHKERRQ(PetscPrintf(PETSC_COMM_SELF," Error norm of |x - z| %e\n",enorm)); 63c4762a1bSJed Brown } 64c4762a1bSJed Brown 65c4762a1bSJed Brown /* Free spaces */ 66*5f80ce2aSJacob Faibussowitsch CHKERRQ(PetscRandomDestroy(&rdm)); 67*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecDestroy(&input)); 68*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecDestroy(&output)); 69*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecDestroy(&x)); 70*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecDestroy(&y)); 71*5f80ce2aSJacob Faibussowitsch CHKERRQ(VecDestroy(&z)); 72*5f80ce2aSJacob Faibussowitsch CHKERRQ(MatDestroy(&A)); 73c4762a1bSJed Brown 74c4762a1bSJed Brown ierr = PetscFinalize(); 75c4762a1bSJed Brown return ierr; 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