Hi Andreas, On 12 July 2010 16:44, Andreas Enge <[email protected]> wrote: > Hi Bill, > > right now, we are thinking about the future license of mpc, and whether > we should switch to LGPLv3+. I was wondering about the potential > implications concerning integration into sage, and to my great amazement, > learnt that mpir switched since version 2.0.0. What was the reason?
Yes, that is correct. The main reason for the switch was so that it is possible for license compatibility with the official GNU project (GMP). In particular we noticed that many talented bignum developers were licensing their code LGPL v3+. Some of this code was desirable for inclusion in MPIR, so only one option remained. None of us really like the license, as we don't understand it. But that is the decision we made, for better of for worse. > I thought that the main "raison d'être" of mpir was to keep a library > under LGPLv2.1+ (and having a more open development model, and better > support of windows). Windows support is far more critical I think. Note that MPIR 1.3 is still released under LGPL v2.1+ though, giving users that option if they wish (though with a slightly outdated version). It is possible that someone may continue work on that version under the same license, though no one has stepped forward to do that at this stage. However, that version cannot benefit from any code that has been added to GMP since it became v3+. The latest version of MPIR can, however, as it is licensed compatibly. > > And do you know what the license situation for sage is? Looking at > COPYING.txt, > it says: "Sage is a compilation both of original Python, C, C++, and Cython > code, and of existing free mathematics-related software. ... Every component > of Sage except jsmath is licensed under a GPL v2 (or later) compatible > license." The rule of thumb is that a library should be *available* under GPL v2+ or compatible license. GPL v3+ is not a showstopper for Sage, only the lack of a GPL v2+ alternative. So long as the v3+ library can be switched out for a v2+ version, then it is fine. It's also a problem for Sage if there is no way for bugs to be fixed in the GPL v2+ version when they are found. The MPIR project has committed to fixing any bugs found in the v2+ version. It's best to ask the Sage project directly about this though. I am only passing on my understanding of the situation, which may change as the Sage developers review the situation. > > I notice that sage-4.4.4 contains mpir-1.2.2; but also gsl-1.10 and > readline-6.0, which are GPLv3. This sounds very much like a contradiction > to the statement above. I am not sure what the story is with gsl and readline, but presumably there are v2+ versions that do just fine for Sage, that can be substituted. I imagine neither is providing an essential service and there is some flexibility. Again I encourage you to check with the Sage devels though to see what the current situation is. Paul Zimmermann may have a better understanding of this than me, as MPFR also changed license (before MPIR did). > > Andreas > Bill. -- You received this message because you are subscribed to the Google Groups "mpir-devel" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/mpir-devel?hl=en.
