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Added a bit of explanation on the fft_shape stuff.

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1 parent 4b5aac4 commit f9604abe4f135f465b2081a6f7e719547e509c4c @hgomersall committed Feb 7, 2012
Showing with 6 additions and 2 deletions.
  1. +6 −2 pyfftw.pyx
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@@ -233,7 +233,7 @@ cdef void _fftwl_destroy_plan(void *_plan):
# Function lookup tables
# ======================
-# Planner table (with the same number of elements as there are schemes).
+# Planner table (of side the number of planners).
cdef fftw_generic_plan_guru planners[9]
cdef fftw_generic_plan_guru * _build_planner_list():
@@ -362,7 +362,11 @@ def _lookup_shape_c2r_arrays(input_array, output_array):
# The 'fft_shape_lookup' function is a callable for returning the
# FFT shape - that is, an array that describes the length of the
# fft along each axis. It has the following signature:
-# fft_shape = fft_shape_lookup(in_array, out_array)
+# fft_shape = fft_shape_lookup(in_array, out_array)
+# (note that this does not correspond to the lengths of the FFT that is
+# actually taken, it's the lengths of the FFT that *could* be taken
+# along each axis. It's necessary because the real FFT has a length
+# that is different to the length of the input array).
fftw_schemes = {
(np.dtype('complex128'), np.dtype('complex128')): 'c128',

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