1*c4762a1bSJed Brown static char help[]="This program illustrates the use of PETSc-fftw interface for real 2D DFT.\n\ 2*c4762a1bSJed Brown See ~petsc/src/mat/tests/ex158.c for general cases. \n\n"; 3*c4762a1bSJed Brown 4*c4762a1bSJed Brown #include <petscmat.h> 5*c4762a1bSJed Brown 6*c4762a1bSJed Brown int main(int argc,char **args) 7*c4762a1bSJed Brown { 8*c4762a1bSJed Brown PetscErrorCode ierr; 9*c4762a1bSJed Brown PetscMPIInt rank,size; 10*c4762a1bSJed Brown PetscInt N0=50,N1=50,N=N0*N1; 11*c4762a1bSJed Brown PetscRandom rdm; 12*c4762a1bSJed Brown PetscReal enorm; 13*c4762a1bSJed Brown Vec x,y,z,input,output; 14*c4762a1bSJed Brown Mat A; 15*c4762a1bSJed Brown PetscInt DIM,dim[2]; 16*c4762a1bSJed Brown PetscReal fac; 17*c4762a1bSJed Brown 18*c4762a1bSJed Brown ierr = PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr; 19*c4762a1bSJed Brown #if defined(PETSC_USE_COMPLEX) 20*c4762a1bSJed Brown SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP, "This example requires real numbers"); 21*c4762a1bSJed Brown #endif 22*c4762a1bSJed Brown 23*c4762a1bSJed Brown ierr = MPI_Comm_size(PETSC_COMM_WORLD, &size);CHKERRQ(ierr); 24*c4762a1bSJed Brown ierr = MPI_Comm_rank(PETSC_COMM_WORLD, &rank);CHKERRQ(ierr); 25*c4762a1bSJed Brown 26*c4762a1bSJed Brown /* Create and set PETSc vectors 'input' and 'output' */ 27*c4762a1bSJed Brown ierr = PetscRandomCreate(PETSC_COMM_WORLD, &rdm);CHKERRQ(ierr); 28*c4762a1bSJed Brown ierr = PetscRandomSetFromOptions(rdm);CHKERRQ(ierr); 29*c4762a1bSJed Brown 30*c4762a1bSJed Brown ierr = VecCreate(PETSC_COMM_WORLD,&input);CHKERRQ(ierr); 31*c4762a1bSJed Brown ierr = VecSetSizes(input,PETSC_DECIDE,N0*N1);CHKERRQ(ierr); 32*c4762a1bSJed Brown ierr = VecSetFromOptions(input);CHKERRQ(ierr); 33*c4762a1bSJed Brown ierr = VecSetRandom(input,rdm);CHKERRQ(ierr); 34*c4762a1bSJed Brown ierr = VecDuplicate(input,&output);CHKERRQ(ierr); 35*c4762a1bSJed Brown ierr = PetscObjectSetName((PetscObject)input, "Real space vector");CHKERRQ(ierr); 36*c4762a1bSJed Brown ierr = PetscObjectSetName((PetscObject)output, "Reconstructed vector");CHKERRQ(ierr); 37*c4762a1bSJed Brown 38*c4762a1bSJed Brown /* Get FFTW vectors 'x', 'y' and 'z' */ 39*c4762a1bSJed Brown DIM = 2; 40*c4762a1bSJed Brown dim[0] = N0; dim[1] = N1; 41*c4762a1bSJed Brown ierr = MatCreateFFT(PETSC_COMM_WORLD,DIM,dim,MATFFTW,&A);CHKERRQ(ierr); 42*c4762a1bSJed Brown ierr = MatCreateVecsFFTW(A,&x,&y,&z);CHKERRQ(ierr); 43*c4762a1bSJed Brown 44*c4762a1bSJed Brown /* Scatter PETSc vector 'input' to FFTW vector 'x' */ 45*c4762a1bSJed Brown ierr = VecScatterPetscToFFTW(A,input,x);CHKERRQ(ierr); 46*c4762a1bSJed Brown 47*c4762a1bSJed Brown /* Apply forward FFT */ 48*c4762a1bSJed Brown ierr = MatMult(A,x,y);CHKERRQ(ierr); 49*c4762a1bSJed Brown 50*c4762a1bSJed Brown /* Apply backward FFT */ 51*c4762a1bSJed Brown ierr = MatMultTranspose(A,y,z);CHKERRQ(ierr); 52*c4762a1bSJed Brown 53*c4762a1bSJed Brown /* Scatter FFTW vector 'z' to PETSc vector 'output' */ 54*c4762a1bSJed Brown ierr = VecScatterFFTWToPetsc(A,z,output);CHKERRQ(ierr); 55*c4762a1bSJed Brown 56*c4762a1bSJed Brown /* Check accuracy */ 57*c4762a1bSJed Brown fac = 1.0/(PetscReal)N; 58*c4762a1bSJed Brown ierr = VecScale(output,fac);CHKERRQ(ierr); 59*c4762a1bSJed Brown ierr = VecAXPY(output,-1.0,input);CHKERRQ(ierr); 60*c4762a1bSJed Brown ierr = VecNorm(output,NORM_1,&enorm);CHKERRQ(ierr); 61*c4762a1bSJed Brown if (enorm > 1.e-11 && !rank) { 62*c4762a1bSJed Brown ierr = PetscPrintf(PETSC_COMM_SELF," Error norm of |x - z| %e\n",enorm);CHKERRQ(ierr); 63*c4762a1bSJed Brown } 64*c4762a1bSJed Brown 65*c4762a1bSJed Brown /* Free spaces */ 66*c4762a1bSJed Brown ierr = PetscRandomDestroy(&rdm);CHKERRQ(ierr); 67*c4762a1bSJed Brown ierr = VecDestroy(&input);CHKERRQ(ierr); 68*c4762a1bSJed Brown ierr = VecDestroy(&output);CHKERRQ(ierr); 69*c4762a1bSJed Brown ierr = VecDestroy(&x);CHKERRQ(ierr); 70*c4762a1bSJed Brown ierr = VecDestroy(&y);CHKERRQ(ierr); 71*c4762a1bSJed Brown ierr = VecDestroy(&z);CHKERRQ(ierr); 72*c4762a1bSJed Brown ierr = MatDestroy(&A);CHKERRQ(ierr); 73*c4762a1bSJed Brown 74*c4762a1bSJed Brown ierr = PetscFinalize(); 75*c4762a1bSJed Brown return ierr; 76*c4762a1bSJed Brown } 77*c4762a1bSJed Brown 78*c4762a1bSJed Brown 79*c4762a1bSJed Brown 80*c4762a1bSJed Brown 81*c4762a1bSJed Brown 82*c4762a1bSJed Brown /*TEST 83*c4762a1bSJed Brown 84*c4762a1bSJed Brown build: 85*c4762a1bSJed Brown requires: fftw !complex 86*c4762a1bSJed Brown 87*c4762a1bSJed Brown test: 88*c4762a1bSJed Brown output_file: output/ex148.out 89*c4762a1bSJed Brown 90*c4762a1bSJed Brown test: 91*c4762a1bSJed Brown suffix: 2 92*c4762a1bSJed Brown nsize: 3 93*c4762a1bSJed Brown output_file: output/ex148.out 94*c4762a1bSJed Brown 95*c4762a1bSJed Brown TEST*/ 96