KokkosFFT::fftshift

template<typename ExecutionSpace, typename ViewType>
void KokkosFFT::fftshift(const ExecutionSpace &exec_space, const ViewType &inout, std::optional<int> axes = std::nullopt)

Shift the zero-frequency component to the center of the spectrum.

Template Parameters:

  • ExecutionSpace – The type of Kokkos execution space

  • ViewType – Input/Output View type for the shift

Parameters:

  • exec_space – [in] Kokkos execution space

  • inout – [in,out] Spectrum

  • axes – [in] Axes over which to shift (default: nullopt, shifting over all axes)

template<typename ExecutionSpace, typename ViewType, std::size_t DIM = 1>
void KokkosFFT::fftshift(const ExecutionSpace &exec_space, const ViewType &inout, axis_type<DIM> axes)

Shift the zero-frequency component to the center of the spectrum.

Template Parameters:

  • ExecutionSpace – The type of Kokkos execution space

  • ViewType – Input/Output View type for the shift

  • DIM – The dimensionality of the shift

Parameters:

  • exec_space – [in] Kokkos execution space

  • inout – [in,out] Spectrum

  • axes – [in] Axes over which to shift

Examples

 1#include <iostream>
 2#include <Kokkos_Core.hpp>
 3#include <Kokkos_Complex.hpp>
 4#include <KokkosFFT.hpp>
 5
 6/// \brief Example of fftshift usage in documentation
 7/// freqs = KokkosFFT::fftfreq(10, 0.1);
 8/// freqs: [0 1 2 3 4 -5 -4 -3 -2 -1]
 9/// KokkosFFT::fftshift(freqs);
10/// freqs_shifted: [-5 -4 -3 -2 -1 0 1 2 3 4]
11int main(int argc, char* argv[]) {
12  Kokkos::ScopeGuard guard(argc, argv);
13  using ExecutionSpace = Kokkos::DefaultExecutionSpace;
14
15  const int n0 = 10;
16  ExecutionSpace exec;
17  auto freq = KokkosFFT::fftfreq(exec, n0, 0.1);
18  KokkosFFT::fftshift(exec, freq);
19  auto h_freq = Kokkos::create_mirror_view_and_copy(Kokkos::HostSpace{}, freq);
20  for (int i = 0; i < freq.extent_int(0); ++i) {
21    std::cout << " " << h_freq(i);
22  }
23  std::cout << std::endl;
24
25  return 0;
26}

Expected output:

-5 -4 -3 -2 -1 0 1 2 3 4