def test_fft(self, backend):
# NOTE: The CPU implementation used by TF is not very accurate, so we
# have to relax the tolerances a little here (default rtol is 1e-5).
rtol = 1e-4
x = np.random.randn(2, 2) + 1J * np.random.randn(2, 2)
x = x.astype('complex64')
y = np.array([[x[0, 0] + x[0, 1] + x[1, 0] + x[1, 1],
x[0, 0] - x[0, 1] + x[1, 0] - x[1, 1]],
[x[0, 0] + x[0, 1] - x[1, 0] - x[1, 1],
x[0, 0] - x[0, 1] - x[1, 0] + x[1, 1]]])
z = backend.fft(x, direction='C2C')
assert np.allclose(y, z, rtol=rtol)
z = backend.fft(x, direction='C2C', inverse=True)
z = z * 4
assert np.allclose(y, z, rtol=rtol)
z = backend.fft(x, direction='C2R', inverse=True)
z = z * 4
assert not np.iscomplexobj(z)
assert np.allclose(np.real(y), z, rtol=rtol)
def test_fft(self, backend):
x = np.random.randn(2, 2) + 1J * np.random.randn(2, 2)
x = x.astype('complex64')
y = np.array([[x[0, 0] + x[0, 1] + x[1, 0] + x[1, 1],
x[0, 0] - x[0, 1] + x[1, 0] - x[1, 1]],
[x[0, 0] + x[0, 1] - x[1, 0] - x[1, 1],
x[0, 0] - x[0, 1] - x[1, 0] + x[1, 1]]])
z = backend.fft(x, direction='C2C')
assert np.allclose(y, z)
z = backend.fft(x, direction='C2C', inverse=True)
z = z * 4
assert np.allclose(y, z)
z = backend.fft(x, direction='C2R', inverse=True)
z = z * 4
assert not np.iscomplexobj(z)
assert np.allclose(np.real(y), z)
def test_fft_exceptions(self, backend):
with pytest.raises(RuntimeError) as record:
backend.fft(np.empty((2, 2)), direction='C2R',
inverse=False)
assert 'done with an inverse' in record.value.args[0]