fourier_common.cpp

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// Copyright (c) 2018 Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
// Copyright (c) 2018 Centre national de la recherche scientifique (CNRS)
// Copyright (c) 2018-2020 Simons Foundation
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You may obtain a copy of the License at
//     https://www.gnu.org/licenses/gpl-3.0.txt
//
// Authors: Michel Ferrero, Nils Wentzell

 
#include "./fourier_common.hpp"
 
namespace triqs::gfs {
 
  void _fourier_base(array_const_view<dcomplex, 2> in, array_view<dcomplex, 2> out, int rank, int *dims, int fftw_count, int fftw_backward_forward) {
 
    // FFTW takes a non-const fftw_complex* even though FFTW_ESTIMATE does not modify the input buffer; the binary
    // layout of dcomplex and fftw_complex is identical, so the casts are safe.
    // NOLINTNEXTLINE(cppcoreguidelines-pro-type-const-cast,cppcoreguidelines-pro-type-reinterpret-cast): required for FFTW C interop
    auto in_fft = reinterpret_cast<fftw_complex *>(const_cast<dcomplex *>(in.data()));
    // NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast): required for FFTW C interop
    auto out_fft = reinterpret_cast<fftw_complex *>(out.data());
 
    auto p = fftw_plan_many_dft(rank,                                          // rank
                                dims,                                          // the dimension
                                fftw_count,                                    // how many FFT : here 1
                                in_fft,                                        // in data
                                nullptr,                                       // embed : unused. Doc unclear ?
                                static_cast<int>(in.indexmap().strides()[0]),  // stride of the in data
                                1,                                             // in : shift for multi fft.
                                out_fft,                                       // out data
                                nullptr,                                       // embed : unused. Doc unclear ?
                                static_cast<int>(out.indexmap().strides()[0]), // stride of the out data
                                1,                                             // out : shift for multi fft.
                                fftw_backward_forward, FFTW_ESTIMATE);
 
    fftw_execute(p);
    fftw_destroy_plan(p);
  }
 
  //void _fourier_base(array_const_view<double, 2> in, array_view<dcomplex, 2> out, int rank, int *dims, int fftw_count) {
 
  //auto in_fft  = reinterpret_cast<fftw_real *>(in.data());
  //auto out_fft = reinterpret_cast<fftw_complex *>(out.data());
 
  //auto p = fftw_plan_many_dft(rank,                        // rank
  //dims,                        // the dimension
  //fftw_count,                  // how many FFT : here 1
  //in_fft,                      // in data
  //NULL,                        // embed : unused. Doc unclear ?
  //in.indexmap().strides()[0],  // stride of the in data
  //1,                           // in : shift for multi fft.
  //out_fft,                     // out data
  //NULL,                        // embed : unused. Doc unclear ?
  //out.indexmap().strides()[0], // stride of the out data
  //1,                           // out : shift for multi fft.
  //FFTW_ESTIMATE);
 
  //fftw_execute(p);
  //fftw_destroy_plan(p);
  //}
 
} // namespace triqs::gfs