Metadata-Version: 1.1
Name: fftlog
Version: 0.2.1
Summary: Logarithmic Fast Fourier Transform
Home-page: https://github.com/prisae/fftlog
Author: Dieter Werthmüller
Author-email: dieter@werthmuller.org
License: CC0-1.0
Description: `fftlog` - A python wrapper for FFTLog
        ======================================
        
        This is a simple `f2py`-wrapper for the logarithmic FFT code *FFTLog* as
        presented in Appendix B of [Hami00]_ and published at
        `casa.colorado.edu/~ajsh/FFTLog <http://casa.colorado.edu/~ajsh/FFTLog>`_.
        
        A pure python version (`pyfftlog`) can be found on `github.com/prisae/pyfftlog
        <https://github.com/prisae/pyfftlog>`_. Tests have shown that `fftlog` is a bit
        faster than `pyfftlog`, but `pyfftlog` is easier to implement, as you only need
        `NumPy` and `SciPy`, without the need to compile anything.
        
        I hope that `FFTLog` will make it into `SciPy` in the future, which will make
        this project redundant. (If you have the bandwidth and are willing to chip in
        have a look at `SciPy PR #7310 <https://github.com/scipy/scipy/pull/7310>`_.)
        
        Be aware that `pyfftlog` has not been tested extensively. It works fine for the
        test from the original code, and my use case, which is `pyfftlog.fftl` with
        `mu=0.5` (sine-transform), `q=0` (unbiased), `k=1`, `kropt=1`, and `tdir=1`
        (forward). Please let me know if you encounter any issues.
        
        - **Documentation**: https://pyfftlog.readthedocs.io
        - **Source Code**: https://github.com/prisae/fftlog
        
        **Note** that the documentation is for the pure python version `pyfftlog`, but
        equally applies to `fftlog`.
        
        Description of FFTLog from the FFTLog-Website
        ---------------------------------------------
        
        FFTLog is a set of fortran subroutines that compute the fast Fourier or Hankel
        (= Fourier-Bessel) transform of a periodic sequence of logarithmically spaced
        points.
        
        FFTLog can be regarded as a natural analogue to the standard Fast Fourier
        Transform (FFT), in the sense that, just as the normal FFT gives the exact (to
        machine precision) Fourier transform of a linearly spaced periodic sequence, so
        also FFTLog gives the exact Fourier or Hankel transform, of arbitrary order m,
        of a logarithmically spaced periodic sequence.
        
        FFTLog shares with the normal FFT the problems of ringing (response to sudden
        steps) and aliasing (periodic folding of frequencies), but under appropriate
        circumstances FFTLog may approximate the results of a continuous Fourier or
        Hankel transform.
        
        The FFTLog algorithm was originally proposed by [Talm78]_.
        
        *For the full documentation, see* `casa.colorado.edu/~ajsh/FFTLog
        <http://casa.colorado.edu/~ajsh/FFTLog>`_.
        
        
        Installation
        ------------
        
        You can install fftlog either via **conda**:
        
        .. code-block:: console
        
           conda install -c conda-forge fftlog
        
        or via **pip**:
        
        .. code-block:: console
        
           pip install fftlog
        
        
        Creation
        --------
        
        The power of `f2py` did most of the work.
        
        The *src*-directory contains the original fortran files as downloaded from
        `casa.colorado.edu/~ajsh/FFTLog <http://casa.colorado.edu/~ajsh/FFTLog>`_.  The
        only change I made was to recode the coding of *fftlog.f*, as `f2py` struggled
        with a few characters in the description part:
        
        .. code:: bash
        
           recode latin1..UTF-8 fftlog.f
        
        Thereafter I used `f2py` to produce the `pyf`-instructions with the following
        command, generating only hooks for the functions `fhti`, `fttl`, `fht`, and
        `fhtq`:
        
        .. code:: bash
        
           f2py src/* -m fftlog -h fftlog.pyf only: fhti fftl fht fhtq :
        
        Lastly I amended the `pyf`-instructions, mainly with some `intent` and
        `optional` statements as well as the corresponding default values.
        
        
        Notes
        '''''
        1. `kropt=3` (interactive adjusting) is not possible with `fftlog`
        2. `wsave`-dimension is set to `2*n+3*(n/2)+19`, the biggest of the four
           minimum sizes described in `fftlog.f`.
        
        
        References
        ----------
        
        .. [Hami00] Hamilton, A. J. S., 2000, Uncorrelated modes of the non-linear
            power spectrum: Monthly Notices of the Royal Astronomical Society, 312,
            pages 257-284; DOI: `10.1046/j.1365-8711.2000.03071.x
            <http://dx.doi.org/10.1046/j.1365-8711.2000.03071.x>`_; Website of FFTLog:
            `casa.colorado.edu/~ajsh/FFTLog <http://casa.colorado.edu/~ajsh/FFTLog>`_.
        
        .. [Talm78] Talman, J. D., 1978, Numerical Fourier and Bessel transforms in
            logarithmic variables: Journal of Computational Physics, 29, pages 35-48;
            DOI: `10.1016/0021-9991(78)90107-9
            <http://dx.doi.org/10.1016/0021-9991(78)90107-9>`_.
        
        
        License, Citation, and Credits
        ------------------------------
        
        These additions to the original FFTLog-code are released to the public domain
        under the `CC0 1.0 License
        <http://creativecommons.org/publicdomain/zero/1.0>`_.
        
        All releases have a Zenodo-DOI, which can be found on `10.5281/zenodo.3830364
        <https://doi.org/10.5281/zenodo.3830534>`_.
        
        Permission to distribute the original Fortran `FFTLog` code with this Python
        `fftlog` package has been granted (email from Andrew Hamilton to Dieter
        WerthmÃ¼ller dated 28 September 2016).
        
        Credits commented in the original code:
        
        `FFTLog` uses the NCAR suite of FFT routines, and a modified version of the
        complex Gamma function from the gamerf package at
        `momonga.t.u-tokyo.ac.jp/~ooura/gamerf.html
        <http://momonga.t.u-tokyo.ac.jp/~ooura/gamerf.html>`_.
        The original gamerf copyright statement states::
        
           Copyright(C) 1996 Takuya OOURA (email: ooura@mmm.t.u-tokyo.ac.jp).
           You may use, copy, modify this code for any purpose and
           without fee. You may distribute this ORIGINAL package.
        
        Permission to distribute the modified gamma function code with the FFTLog
        package has been granted (email from Takuya Ooura to Andrew Hamilton dated 16
        March 1999).
        
        Be kind and give credits by citing Hamilton (2000).
        
Platform: UNKNOWN
Classifier: Development Status :: 5 - Production/Stable
Classifier: License :: CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
