[SciPy-Dev] Fast Walsh–Hadamard transform for SciPy ?

[Chaman Agrawal]

Hello,

Thanks, please send the link ,it would be good to have multiple references.

However the important part is where to implement this ,in fftpack or signal
as Ralf Gommers <https://github.com/rgommers> mentioned in the issue page.

Cheers,
Chaman
I have my own code for FHT if you are interested

On Thu, Mar 22, 2018 at 2:52 PM Chaman Agrawal <chaman.ag at gmail.com
<https://mail.python.org/mailman/listinfo/scipy-dev>> wrote:

>* Issue #8590 https://github.com/scipy/scipy/issues/8590 <https://github.com/scipy/scipy/issues/8590>
*>>* Currently there is no implementation of Fast Walsh–Hadamard transform in
*>* SciPy. Although it seems that FWHT is not as general as FFT but it is
*>* pretty ubiquitous ,it is there is other maths and science softwares like
*>* MATLAB etc. .I would like to contribute towards it. Following are the
*>* details about it.
*>* Fast Walsh–Hadamard transform
*>>* Hadamard transform is an example of a generalized class of Fourier
*>* transforms. It performs an orthogonal, symmetric, involutive, linear
*>* operation on 2^(m) numbers. It is equivalent to a multidimensional DFT.
*>* Time Complexity:
*>>* O(nlogn) with Fast Walsh-Hadamard transform (FWHT)
*>* Comparison with FFT:
*>>* FWHT is very useful for reducing bandwidth storage requirements and
*>* spread-spectrum analysis. Compared to the FFT, the FWHT requires less
*>* storage space and is faster to calculate because it uses only real
*>* additions and subtractions, while the FFT requires complex values. The FWHT
*>* is able to represent signals with sharp discontinuities more accurately
*>* using fewer coefficients than the FFT.
*>* Some Usage examples:
*>>* The Hadamard transform is used in data encryption, as well as many signal
*>* processing and data compression algorithms, such as JPEG XR and MPEG-4 AVC.
*>* It is also a crucial part of Grover's algorithm and Shor's algorithm in
*>* quantum computing. The Hadamard transform is also applied in scientific
*>* methods such as NMR, mass spectroscopy and crystallography.
*>
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