/*

* xtensor-fftw

* Copyright (c) 2017, Patrick Bos

* Distributed under the terms of the BSD 3-Clause License.

*

* The full license is in the file LICENSE, distributed with this software.

*/

#define _USE_MATH_DEFINES // for MSVC ("Math Constants are not defined in Standard C/C++")

#include <cmath> // M_PI

#include <xtensor/xarray.hpp>

#include <xtensor-fftw/helper.hpp>

#include "gtest/gtest.h"

TEST(helper, fftshift) {

xt::xarray<double> odd = {3, 4, 0, 1, 2};

xt::xarray<double> even = {3, 4, 5, 0, 1, 2};

xt::xarray<double> odd_range = xt::arange<double>(5);

xt::xarray<double> even_range = xt::arange<double>(6);

EXPECT_EQ(xt::fftw::fftshift(odd_range), odd);

EXPECT_EQ(xt::fftw::fftshift(even_range), even);

}

TEST(helper, ifftshift) {

xt::xarray<double> odd = {3, 4, 0, 1, 2};

xt::xarray<double> even = {3, 4, 5, 0, 1, 2};

EXPECT_EQ(xt::fftw::ifftshift(odd), xt::arange<double>(5));

EXPECT_EQ(xt::fftw::ifftshift(even), xt::arange<double>(6));

}

TEST(helper, fftfreq) {

xt::xarray<double> reference9 = {0., 1., 2., 3., 4., -4., -3., -2., -1.};

xt::xarray<double> reference10 = {0. , 0.04, 0.08, 0.12, 0.16, -0.2 , -0.16, -0.12, -0.08, -0.04};

EXPECT_EQ(xt::fftw::fftfreq(9, 1./9), reference9);

EXPECT_EQ(xt::fftw::fftfreq(10, 2.5), reference10);

}

TEST(helper, fftscale) {

xt::xarray<double> reference9 = {0., 1., 2., 3., 4., -4., -3., -2., -1.};

xt::xarray<double> reference10 = {0. , 0.04, 0.08, 0.12, 0.16, -0.2 , -0.16, -0.12, -0.08, -0.04};

EXPECT_EQ(xt::fftw::fftscale(9, 1./9), 2 * M_PI * reference9);

EXPECT_EQ(xt::fftw::fftscale(10, 2.5), 2 * M_PI * reference10);

}

TEST(helper, rfftfreq) {

xt::xarray<double> reference9 = {0., 1., 2., 3., 4.};

xt::xarray<double> reference10 = {0. , 0.04, 0.08, 0.12, 0.16, 0.2};

EXPECT_EQ(xt::fftw::rfftfreq(9, 1./9), reference9);

EXPECT_EQ(xt::fftw::rfftfreq(10, 2.5), reference10);

}

TEST(helper, rfftscale) {

xt::xarray<double> reference9 = {0., 1., 2., 3., 4.};

xt::xarray<double> reference10 = {0. , 0.04, 0.08, 0.12, 0.16, 0.2};

EXPECT_EQ(xt::fftw::rfftscale(9, 1./9), 2 * M_PI * reference9);

EXPECT_EQ(xt::fftw::rfftscale(10, 2.5), 2 * M_PI * reference10);

}