On Fri, Apr 30, 2010 at 4:11 AM, Sergey Bochkanov <sergey.bochka...@alglib.net> wrote: > Hello, William. > >> In Sage we (=mostly Gonzalo Tornaria) spent an enormous amount of time >> writing two very efficient C functions, one to convert from mpz to >> Python ints, and one to convert back. Yes, writing this code is a >> lot of work. But no, the resulting code is not slow. Just because >> something is hard doesn't mean "we can't do it". >> If you want this code, I bet Gonzalo would be OK with letting you have >> it under another license (it's GPL v2+ right now); it's not long, just >> tricky to write. > > That would be nice. Currently X-MPIR is licensed under LGPL, but I > think that the same automatic codegen technology may be applied to > other projects under different licenses. So having this code under > something BSD-like would be important step in Python support.
Although I'm more of a GPL (v2) type, and I wouldn't write BSD code unless I had a very good reason, I could consider relicensing some interface code like this. I've actually relicensed this code to LGPL v2+ (for gmpy), but I'm not sure I can go farther than that, since my code was based on GMP code (itself LGPL v2+ at the time). See the forwarded message below for details. Best, Gonzalo ---------- Forwarded message ---------- From: Gonzalo Tornaria <torna...@math.utexas.edu> Date: Tue, Sep 8, 2009 at 10:58 PM Subject: Re: mpmath and files To: William Stein <wst...@gmail.com> Cc: casevh <cas...@gmail.com>, mpm...@googlegroups.com On Tue, Sep 8, 2009 at 8:54 PM, William Stein<wst...@gmail.com> wrote: > On Tue, Sep 8, 2009 at 4:38 PM, casevh<cas...@gmail.com> wrote: >> On Sep 7, 5:00 pm, William Stein <wst...@gmail.com> wrote: >>> I think there is very complicated highly optimized code somewhere in Sage >>> (http://sagemath.org) for conversion between Python longs and GMP >>> mpz_t's. If this is what you need, it could be dug up. >> >> I maintain gmpy, the Python wrapper for GMP or MPIR, and I would like >> to look at including Sage's conversion code. I'm currently using >> mpz_import and mpz_export and am always looking for faster code. >> >> Case Van Horsen >> > > Hi, > > Look in the src and include directories here: > > http://sage.math.washington.edu/home/wstein/build/sage-4.1.1/devel/sage/c_lib/ > >> Would there be any licensing issues since gmpy is LGPL2+? > > Yes, there is a problem since the code is licensed GPL2+. However, > I've cc'd the author -- Gonzalo Tornaria -- and I bet he would be > willing to contribute a LGPL2+ version of the code to gmpy. I > certainly endorse that! I can definitely contribute the mpz<-->pylong conversion code to gmpy under LGPL2+. You want to look at the files mpn_pylong.c and mpz_pylong.c. The high level interface (mpz <-> pylong) is given by functions mpz_get_pylong() and mpz_set_pylong(). There's also a function mpz_pythonhash() which computes a python-compatible hash of mpz integers. The function mpz_get_pyintlong() is a variation of mpz_get_pylong() written by David Harvey --- you should ask him about that one. Note also that the base conversion code used in mpn_get_pylong() is based on GMP code --- I think GMP was LGPLv2+ at the time, so it should be fine. Let me know if you have any issues with using this code in gmpy. If you use the code, can you add a comment to the files along these lines: """ Originally written for sage (http://sagemath.org) -- if you improve these functions, please contribute them back to sage by posting to sage-devel@googlegroups.com or sending me an email. """ Best, Gonzalo -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
