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#!/usr/bin/env python
# Copied from fftpack.helper by Pearu Peterson, October 2005
""" Test functions for fftpack.helper module
"""
from numpy.testing import *
from numpy.fft import fftshift,ifftshift,fftfreq
from numpy import pi
def random(size):
return rand(*size)
class TestFFTShift(TestCase):
def test_definition(self):
x = [0,1,2,3,4,-4,-3,-2,-1]
y = [-4,-3,-2,-1,0,1,2,3,4]
assert_array_almost_equal(fftshift(x),y)
assert_array_almost_equal(ifftshift(y),x)
x = [0,1,2,3,4,-5,-4,-3,-2,-1]
y = [-5,-4,-3,-2,-1,0,1,2,3,4]
assert_array_almost_equal(fftshift(x),y)
assert_array_almost_equal(ifftshift(y),x)
def test_inverse(self):
for n in [1,4,9,100,211]:
x = random((n,))
assert_array_almost_equal(ifftshift(fftshift(x)),x)
def test_axes_keyword(self):
freqs = [[ 0, 1, 2], [ 3, 4, -4], [-3, -2, -1]]
shifted = [[-1, -3, -2], [ 2, 0, 1], [-4, 3, 4]]
assert_array_almost_equal(fftshift(freqs, axes=(0, 1)), shifted)
assert_array_almost_equal(fftshift(freqs, axes=0), fftshift(freqs, axes=(0,)))
assert_array_almost_equal(ifftshift(shifted, axes=(0, 1)), freqs)
assert_array_almost_equal(ifftshift(shifted, axes=0), ifftshift(shifted, axes=(0,)))
class TestFFTFreq(TestCase):
def test_definition(self):
x = [0,1,2,3,4,-4,-3,-2,-1]
assert_array_almost_equal(9*fftfreq(9),x)
assert_array_almost_equal(9*pi*fftfreq(9,pi),x)
x = [0,1,2,3,4,-5,-4,-3,-2,-1]
assert_array_almost_equal(10*fftfreq(10),x)
assert_array_almost_equal(10*pi*fftfreq(10,pi),x)
if __name__ == "__main__":
run_module_suite()
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