def check_djbfft(self):
from numpy.fft import ifft as numpy_ifft
for i in range(2, 14):
n = 2 ** i
x = range(n)
x1 = zeros((n,), dtype=cdouble)
x1[0] = x[0]
for k in range(1, n / 2):
x1[k] = x[2 * k - 1] + 1j * x[2 * k]
x1[n - k] = x[2 * k - 1] - 1j * x[2 * k]
x1[n / 2] = x[-1]
y1 = numpy_ifft(x1)
y = fftpack.drfft(x, direction=-1)
assert_array_almost_equal(y, y1)
def check_djbfft(self):
from numpy.fft import fft as numpy_fft
for i in range(2, 14):
n = 2 ** i
x = range(n)
y2 = numpy_fft(x)
y1 = zeros((n,), dtype=double)
y1[0] = y2[0].real
y1[-1] = y2[n / 2].real
for k in range(1, n / 2):
y1[2 * k - 1] = y2[k].real
y1[2 * k] = y2[k].imag
y = fftpack.drfft(x)
assert_array_almost_equal(y, y1)