.. module:: cupyx.scipy.fft Discrete Fourier transforms (:mod:`cupyx.scipy.fft`) ==================================================== .. Hint:: `SciPy API Reference: Discrete Fourier transforms (scipy.fft) `_ .. seealso:: :doc:`../user_guide/fft` Fast Fourier Transforms (FFTs) ------------------------------ .. autosummary:: :toctree: generated/ fft ifft fft2 ifft2 fftn ifftn rfft irfft rfft2 irfft2 rfftn irfftn hfft ihfft hfft2 ihfft2 hfftn ihfftn Discrete Cosine and Sine Transforms (DST and DCT) ------------------------------------------------- .. autosummary:: :toctree: generated/ dct idct dctn idctn dst idst dstn idstn Fast Hankel Transforms ---------------------- .. autosummary:: :toctree: generated/ fht ifht Helper functions ---------------- .. autosummary:: :toctree: generated/ fftshift ifftshift fftfreq rfftfreq next_fast_len Code compatibility features --------------------------- 1. As with other FFT modules in CuPy, FFT functions in this module can take advantage of an existing cuFFT plan (returned by :func:`~cupyx.scipy.fftpack.get_fft_plan`) to accelerate the computation. The plan can be either passed in explicitly via the keyword-only ``plan`` argument or used as a context manager. One exception to this are the DCT and DST transforms, which do not currently support a plan argument. 2. The boolean switch ``cupy.fft.config.enable_nd_planning`` also affects the FFT functions in this module, see :doc:`./fft`. This switch is neglected when planning manually using :func:`~cupyx.scipy.fftpack.get_fft_plan`. 3. Like in ``scipy.fft``, all FFT functions in this module have an optional argument ``overwrite_x`` (default is ``False``), which has the same semantics as in ``scipy.fft``: when it is set to ``True``, the input array ``x`` *can* (not *will*) be overwritten arbitrarily. For this reason, when an in-place FFT is desired, the user should always reassign the input in the following manner: ``x = cupyx.scipy.fftpack.fft(x, ..., overwrite_x=True, ...)``. 4. The ``cupyx.scipy.fft`` module can also be used as a backend for ``scipy.fft`` e.g. by installing with ``scipy.fft.set_backend(cupyx.scipy.fft)``. This can allow ``scipy.fft`` to work with both ``numpy`` and ``cupy`` arrays. For more information, see :ref:`scipy_fft_backend`. 5. The boolean switch :data:`cupy.fft.config.use_multi_gpus` also affects the FFT functions in this module, see :doc:`./fft`. Moreover, this switch is *honored* when planning manually using :func:`~cupyx.scipy.fftpack.get_fft_plan`. 6. Both type II and III DCT and DST transforms are implemented. Type I and IV transforms are currently unavailable.