nlcpy.fft.rfftn
- nlcpy.fft.rfftn(a, s=None, axes=None, norm=None)[ソース]
Computes the n-dimensional discrete fourier transform for a real array.
This function computes the n-dimensional discrete fourier transform over any number of axes in an m-dimensional real array by means of the fast fourier transform (FFT). By default, all axes are transformed, with the real transform performed over the last axis, while the remaining transforms are complex.
- Parameters
- aarray_like
Input array, taken to be real.
- ssequence of int, optional
Shape (length along each transformed axis) to use from the input. (
s[0]
refers to axis 0,s[1]
to axis 1, etc.). The final element of s corresponds to n forrfft(x, n)
, while for the remaining axes, it corresponds to n forfft(x, n)
. Along any axis, if the given shape is smaller than that of the input, the input is cropped. If it is larger, the input is padded with zeros. If s is not given, the shape of the input along the axes specified by axes is used. If s and axes have different length, ValueError occurs.- axessequence of ints, optional
Axes over which to compute the FFT. If not given, the last
len(s)
axes are used, or all axes if s is also not specified. If an element of axes is larger than than the number of axes of a, IndexError occurs.- norm{None, "ortho"},optional
Normalization mode. By default(None), the transforms are unscaled. It norm is set to "ortho", the return values will be scaled by .
- Returns
- outcomplex ndarray
The truncated or zero-padded input, transformed along the axes indicated by axes, or by a combination of s and a, as explained in the parameters section above. The length of the last axis transformed will be
s[-1]//2+1
, while the remaining transformed axes will have lengths according to s, or unchanged from the input.
参考
irfftn
Computes the inverse of the n-dimensional FFT of a real array.
fft
Computes the one-dimensional discrete fourier transform.
rfft
Computes the one-dimensional discrete fourier transform for a real array.
fftn
Computes the n-dimensional discrete fourier transform.
rfft2
Computes the 2-dimensional FFT of a real array.
注釈
The transform for a real array is performed over the last transformation axis, as by
rfft()
, then the transform over the remaining axes is performed as byfftn()
. The order of the output is as forrfft()
for the final transformation axis, and as forfftn()
for the remaining transformation axes. Seefft()
for details, definitions and conventions used.Examples
>>> import nlcpy as vp >>> a = vp.ones((2, 2, 2)) >>> vp.fft.rfftn(a) array([[[8.+0.j, 0.+0.j], # may vary [0.+0.j, 0.+0.j]], [[0.+0.j, 0.+0.j], [0.+0.j, 0.+0.j]]]) >>> vp.fft.rfftn(a, axes=(2, 0)) array([[[4.+0.j, 0.+0.j], # may vary [4.+0.j, 0.+0.j]], [[0.+0.j, 0.+0.j], [0.+0.j, 0.+0.j]]])