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fftlog-0.2.1
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Logarithmic Fast Fourier Transform
| ویژگی | مقدار |
|---|---|
| سیستم عامل | - |
| نام فایل | fftlog-0.2.1 |
| نام | fftlog |
| نسخه کتابخانه | 0.2.1 |
| نگهدارنده | [] |
| ایمیل نگهدارنده | [] |
| نویسنده | Dieter Werthmüller |
| ایمیل نویسنده | dieter@werthmuller.org |
| آدرس صفحه اصلی | https://github.com/prisae/fftlog |
| آدرس اینترنتی | https://pypi.org/project/fftlog/ |
| مجوز | CC0-1.0 |
`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
Werthmüller 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).
نحوه نصب
نصب پکیج whl fftlog-0.2.1:
pip install fftlog-0.2.1.whl
نصب پکیج tar.gz fftlog-0.2.1:
pip install fftlog-0.2.1.tar.gz