Compute the N-dimensional inverse discrete Fourier Transform. This function computes the inverse of the N-dimensional discrete Fourier Transform over any number of axes in an M-dimensional array by means of the Fast Fourier Transform (FFT). In other words, ``ifftn(fftn(a)) ==
(a, s=None, axes=None, norm=None, out=None)
| 886 | |
| 887 | @array_function_dispatch(_fftn_dispatcher) |
| 888 | def ifftn(a, s=None, axes=None, norm=None, out=None): |
| 889 | """ |
| 890 | Compute the N-dimensional inverse discrete Fourier Transform. |
| 891 | |
| 892 | This function computes the inverse of the N-dimensional discrete |
| 893 | Fourier Transform over any number of axes in an M-dimensional array by |
| 894 | means of the Fast Fourier Transform (FFT). In other words, |
| 895 | ``ifftn(fftn(a)) == a`` to within numerical accuracy. |
| 896 | For a description of the definitions and conventions used, see `numpy.fft`. |
| 897 | |
| 898 | The input, analogously to `ifft`, should be ordered in the same way as is |
| 899 | returned by `fftn`, i.e. it should have the term for zero frequency |
| 900 | in all axes in the low-order corner, the positive frequency terms in the |
| 901 | first half of all axes, the term for the Nyquist frequency in the middle |
| 902 | of all axes and the negative frequency terms in the second half of all |
| 903 | axes, in order of decreasingly negative frequency. |
| 904 | |
| 905 | Parameters |
| 906 | ---------- |
| 907 | a : array_like |
| 908 | Input array, can be complex. |
| 909 | s : sequence of ints, optional |
| 910 | Shape (length of each transformed axis) of the output |
| 911 | (``s[0]`` refers to axis 0, ``s[1]`` to axis 1, etc.). |
| 912 | This corresponds to ``n`` for ``ifft(x, n)``. |
| 913 | Along any axis, if the given shape is smaller than that of the input, |
| 914 | the input is cropped. If it is larger, the input is padded with zeros. |
| 915 | |
| 916 | .. versionchanged:: 2.0 |
| 917 | |
| 918 | If it is ``-1``, the whole input is used (no padding/trimming). |
| 919 | |
| 920 | If `s` is not given, the shape of the input along the axes specified |
| 921 | by `axes` is used. See notes for issue on `ifft` zero padding. |
| 922 | |
| 923 | .. deprecated:: 2.0 |
| 924 | |
| 925 | If `s` is not ``None``, `axes` must not be ``None`` either. |
| 926 | |
| 927 | .. deprecated:: 2.0 |
| 928 | |
| 929 | `s` must contain only ``int`` s, not ``None`` values. ``None`` |
| 930 | values currently mean that the default value for ``n`` is used |
| 931 | in the corresponding 1-D transform, but this behaviour is |
| 932 | deprecated. |
| 933 | |
| 934 | axes : sequence of ints, optional |
| 935 | Axes over which to compute the IFFT. If not given, the last ``len(s)`` |
| 936 | axes are used, or all axes if `s` is also not specified. |
| 937 | Repeated indices in `axes` means that the inverse transform over that |
| 938 | axis is performed multiple times. |
| 939 | |
| 940 | .. deprecated:: 2.0 |
| 941 | |
| 942 | If `s` is specified, the corresponding `axes` to be transformed |
| 943 | must be explicitly specified too. |
| 944 | |
| 945 | norm : {"backward", "ortho", "forward"}, optional |
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