Hi, Unfortunately I don't think those notes are particularly helpful in this regard: for example, does bundling the software with SciPy meet the requirement of "distributing the ORIGINAL package", or not? It's murky, and most of the devs would likely err on the side of safety and assume the answer is no. The benefit of using an established license like BSD, MIT, GPL, etc. is that the language is well-defined and the intent of the license is well-understood. Jake Jake VanderPlas Senior Data Science Fellow Director of Research in Physical Sciences University of Washington eScience Institute On Fri, Oct 7, 2016 at 11:24 AM, Dieter Werthmüller <dieter@werthmuller.org> wrote:

Jake,

Thanks for your reply.

Have you seen my whole section on "Files and Licences/Permissions"? (I put that info at the end of my original message, after my name.) Do you think it is not enough if Hamilton gave his written permission to 'use fftlog in any way you choose'?

Dieter

Hi Dieter, That's very cool! Before discussion of whether this fits into SciPy, there's one issue: I don't see any license on the Fortran code. This means, unfortunately, that it defaults to some form of "all-rights-reserved" and cannot be used in SciPy.

Often it's enough to email the package author, link to some information like my post at [1], and request that they add a BSD-style license to their code (note that a GPL-style license would make it unusable by SciPy).

Though we may want to see what others think about including this in SciPy before going too far down that route. For what it's worth, I'd suggest starting by making sure your Python wrapper is well-documented & well-tested; if it proves useful to many people, it would then be quite easy to pull into SciPy.

Jake

[1] http://www.astrobetter.com/blog/2014/03/10/the-whys-and- hows-of-licensing-scientific-code/

Jake VanderPlas Senior Data Science Fellow Director of Research in Physical Sciences University of Washington eScience Institute

On Thu, Oct 6, 2016 at 7:20 PM, Dieter Werthmüller <dieter@werthmuller.org <mailto:dieter@werthmuller.org>> wrote:

Dear SciPy-devs,

I recently had the need for a logarithmic FFT routine, and did a quick f2py around Andrew Hamilton's FFTLog: http://casa.colorado.edu/~ajsh/FFTLog <http://casa.colorado.edu/~ajsh/FFTLog>

I put my f2py-setup and my pyf-file up on GitHub: https://github.com/prisae/fftlog <https://github.com/prisae/fftlog

I thought it might be a useful addition to the SciPy FFTPack. Specifically as three out of the five fortran-files, of which FFTLog consists, are already in scipy/fftpack.

I have never contributed to SciPy and therefore do not know how much work it would involve to get it into SciPy. However, I thought I ask. If there is interest I expect that it would not take long for an experienced person, as it is a fairly small addition. Or someone could point me to the right direction on what to do to get it in.

I append some comments on the involved files of FFTLog and some comments regarding their licenses. I believe it is compatible with SciPy.

Thanks for all your good work! Dieter

Files and Licenses/Permissions ------------------------------

Files of FFTLog

[1] cdgamma.f [2] drfftb.f [3] drfftf.f [4] drffti.f [5] fftlog.f

(plus a test routine, fftlogtest.f)

-- [1] -- The original FFTLog states about this file:

FFTLog uses [...] 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 <mailto: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).

Hence I think it is compatible with SciPy, or am I wrong?

Alternatively it could be replaced with scipy.special.loggamma, I think, but I do not know if it is possible to mix Fortran and Python code with f2py.

-- [2], [3], [4] -- They are from the NCAR suite of FFT routines (Swarztrauber 1979).

As far as I can see they are already in SciPy, in scipy/fftpack/src/dfftpack/ (dfftb.f, dfftf.f, and dffti.f).

So there is definitely not a licensing problem here.

-- [5] -- This is the actual FFTLog routine from Hamilton.

I asked Hamilton for permission before publishing his source code at github.com/prisae/fftlog <http://github.com/prisae/fftlog>.

His email response was:

-- start email from 28/09/2016 -- Dieter,

You are welcome to use fftlog in any way you choose. Please note

On 07/10/16 12:53, Jacob Vanderplas wrote: the

credits commented in the code:

c FFTLog uses the NCAR suite of FFT routines, c and a modified version of the complex Gamma function c from the gamerf package at c http://momonga.t.u-tokyo.ac.jp/~ooura/gamerf.html <http://momonga.t.u-tokyo.ac.jp/~ooura/gamerf.html> . c The original gamerf copyright statement states: c Copyright(C) 1996 Takuya OOURA (email: ooura@mmm.t.u-tokyo.ac.jp <mailto:ooura@mmm.t.u-tokyo.ac.jp>). c You may use, copy, modify this code for any purpose and c without fee. You may distribute this ORIGINAL package. c c Permission to distribute the modified gamma function code c with the FFTLog package has been granted c (email from Takuya Ooura to Andrew Hamilton dated 16 March 1999).

Andrew -- end email from 28/09/2016 --

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