Can't find the examples/dftf/ directory in my MKL install

brianreinhold — Mon, 15 Sep 2025 11:08:17 GMT

I just installed the standalone MKL and it did not include the examples/dftf/ directory. The MKL developers guide says it should exist. Where can I get these examples or are they now gone?

Re: Can't find the examples/dftf/ directory in my MKL install

Spencer_P_Intel — Mon, 15 Sep 2025 15:47:35 GMT

Examples live in the <mkl root>/share/doc/mkl/examples folder. There you will find dftf/ folder by unpacking the examples_core_f.tgz archive (or equivalent if you are on Windows).

Re: Can't find the examples/dftf/ directory in my MKL install

brianreinhold — Tue, 16 Sep 2025 22:33:08 GMT

Thank you! It's good to have those. My plan routine compiled and built but was totally different than the example. I don't understand how it built.

After looking at the examples I changed my routine to

module Fftw3HelpersModule use, intrinsic :: iso_c_binding implicit none ! FFTW plan handles for different transforms integer*8 :: plan_spectral_to_grid_sin = 0 integer*8 :: plan_grid_to_spectral_sin = 0 integer*8 :: plan_spectral_to_grid_cos = 0 integer*8 :: plan_grid_to_spectral_cos = 0 integer*8 :: plan_spectral_to_grid_zonal_1d = 0 integer*8 :: plan_grid_to_spectral_zonal_1d = 0 contains subroutine setup_fftw_plans(Nx, Ny) use, intrinsic :: iso_c_binding implicit none include 'fftw3.f' include 'fftw3_mkl.f' integer(c_int), intent(in) :: Nx, Ny real(C_FLOAT), allocatable :: dummy(:, :) real(C_FLOAT), allocatable :: dummy_1d(:) ! Cleanup existing plans if (plan_spectral_to_grid_sin .NE. 0) call sfftw_destroy_plan(plan_spectral_to_grid_sin) if (plan_grid_to_spectral_sin .NE. 0) call sfftw_destroy_plan(plan_grid_to_spectral_sin) if (plan_spectral_to_grid_cos .NE. 0) call sfftw_destroy_plan(plan_spectral_to_grid_cos) if (plan_grid_to_spectral_cos .NE. 0) call sfftw_destroy_plan(plan_grid_to_spectral_cos) if (plan_spectral_to_grid_zonal_1d .NE. 0) call sfftw_destroy_plan(plan_spectral_to_grid_zonal_1d) if (plan_grid_to_spectral_zonal_1d .NE. 0) call sfftw_destroy_plan(plan_grid_to_spectral_zonal_1d) allocate(dummy(Ny, Nx)) allocate(dummy_1d(Ny)) ! Plans for sin(kx)sin(ly) and cos(kx)sin(ly) components call sfftw_plan_r2r_2d(plan_grid_to_spectral_sin, Ny, Nx, dummy, dummy, FFTW_RODFT00, FFTW_R2HC, FFTW_MEASURE) ! MKL_RODFT00 call sfftw_plan_r2r_2d(plan_spectral_to_grid_sin, Ny, Nx, dummy, dummy, FFTW_RODFT00, FFTW_HC2R, FFTW_MEASURE) ! Plans for sin(kx)cos(ly) and cos(kx)cos(ly) components call sfftw_plan_r2r_2d(plan_grid_to_spectral_cos, Ny, Nx, dummy, dummy, FFTW_REDFT00, FFTW_R2HC, FFTW_MEASURE) call sfftw_plan_r2r_2d(plan_spectral_to_grid_cos, Ny, Nx, dummy, dummy, FFTW_REDFT00, FFTW_HC2R, FFTW_MEASURE) ! Plans for zonal flow components cos(ly). call sfftw_plan_r2r_1d(plan_grid_to_spectral_zonal_1d, Ny, dummy_1d, dummy_1d, FFTW_REDFT00, FFTW_MEASURE) call sfftw_plan_r2r_1d(plan_spectral_to_grid_zonal_1d, Ny, dummy_1d, dummy_1d, FFTW_REDFT00, FFTW_MEASURE) deallocate(dummy) deallocate(dummy_1d) end subroutine setup_fftw_plans end module Fftw3HelpersModule

It was

module Fftw3HelpersModule use, intrinsic :: iso_c_binding implicit none include 'fftw3.f03' ! FFTW plan handles for different transforms type(c_ptr) :: plan_spectral_to_grid_sin, plan_grid_to_spectral_sin type(c_ptr) :: plan_spectral_to_grid_cos, plan_grid_to_spectral_cos type(c_ptr) :: plan_spectral_to_grid_zonal_1d, plan_grid_to_spectral_zonal_1d contains subroutine setup_fftw_plans(Nx, Ny) use, intrinsic :: iso_c_binding implicit none include 'fftw3.f03' integer(c_int), intent(in) :: Nx, Ny real(C_FLOAT), allocatable :: dummy(:, :) real(C_FLOAT), allocatable :: dummy_1d(:) ! Cleanup existing plans if (c_associated(plan_spectral_to_grid_sin)) call fftw_destroy_plan(plan_spectral_to_grid_sin) if (c_associated(plan_grid_to_spectral_sin)) call fftw_destroy_plan(plan_grid_to_spectral_sin) if (c_associated(plan_spectral_to_grid_cos)) call fftw_destroy_plan(plan_spectral_to_grid_cos) if (c_associated(plan_grid_to_spectral_cos)) call fftw_destroy_plan(plan_grid_to_spectral_cos) if (c_associated(plan_spectral_to_grid_zonal_1d)) call fftw_destroy_plan(plan_spectral_to_grid_zonal_1d) if (c_associated(plan_grid_to_spectral_zonal_1d)) call fftw_destroy_plan(plan_grid_to_spectral_zonal_1d) allocate(dummy(Ny, Nx)) allocate(dummy_1d(Ny)) ! Plans for sin(kx)sin(ly) and cos(kx)sin(ly) components plan_grid_to_spectral_sin = fftwf_plan_r2r_2d(Ny, Nx, dummy, dummy, FFTW_RODFT00, FFTW_R2HC, FFTW_MEASURE) plan_spectral_to_grid_sin = fftwf_plan_r2r_2d(Ny, Nx, dummy, dummy, FFTW_RODFT00, FFTW_HC2R, FFTW_MEASURE) ! Plans for sin(kx)cos(ly) and cos(kx)cos(ly) components plan_grid_to_spectral_cos = fftwf_plan_r2r_2d(Ny, Nx, dummy, dummy, FFTW_REDFT00, FFTW_R2HC, FFTW_MEASURE) plan_spectral_to_grid_cos = fftwf_plan_r2r_2d(Ny, Nx, dummy, dummy, FFTW_REDFT00, FFTW_HC2R, FFTW_MEASURE) ! Plans for zonal flow components cos(ly). plan_grid_to_spectral_zonal_1d = fftwf_plan_r2r_1d(Ny, dummy_1d, dummy_1d, FFTW_REDFT00, FFTW_MEASURE) plan_spectral_to_grid_zonal_1d = fftwf_plan_r2r_1d(Ny, dummy_1d, dummy_1d, FFTW_REDFT00, FFTW_MEASURE) deallocate(dummy) deallocate(dummy_1d) end subroutine setup_fftw_plans end module Fftw3HelpersModule

I am assuming the changes I made to follow the examples are correct.

topic Re: Can't find the examples/dftf/ directory in my MKL install in Intel® oneAPI Math Kernel Library

Can't find the examples/dftf/ directory in my MKL install

Re: Can't find the examples/dftf/ directory in my MKL install

Re: Can't find the examples/dftf/ directory in my MKL install