On 9/23/07, Jason Martin <[EMAIL PROTECTED]> wrote:
> Some thoughts:
>
> 1. I've been doing some performance comparisons on GMP 4.2.2 with the
> patches that Sage uses, and I haven't seen any remarkable differences
> between 4.2.2 and 4.2.1. Granted, I have only tested Linux on
> AMD64/Intel64 and OS X on Intel64. Perhaps some other platforms have
> a greater difference. (By the way, the GPL patches for gcd/xgcd seem
> to work just fine.)
Is GMP-4.2.1 with the gcd/xgcd patch vastly faster than GMP-4.2.2 at
what the gcd patch is for (i.e., gcd's of million digit numbers)?
> It is nice that it will compile under OS X now without patching... and
> it even builds dynamic libraries. It is somewhat slow without
> patches, though.
Do you mean that GMP-4.2.2 is somewhat slow without patches?
Or that GMP-4.2.1 is? Or?
> 2. I suspect that the GMP developers were very deliberate in their
> license choice and will not release it under "LGPLv2 or greater".
> Much of the v2/3 license debate hinges on DRM issues: public key
> crypto is a big part of most DRM systems, and GMP is a natural choice
> for implementing public key crypto... but it can't hurt to ask.
I think GMP is not going to change to LGPLv2 or greater; switching
from LGPLv2 or greater to LGPLv3 is the one and only new "big feature"
of GMP 4.2.2 (see the release notes).
Also -- much more importantly, the copyright owners of GMP
are the Free Software Foundation -- not "the GMP developers",
and their agenda is very clear.
> 3. How much of Sage is under "v2 Only"? That's the only portion that
> should cause problems isn't it?
Good question. First, how do we determine if something is v2 only?
>From the GPL itself: "Each version is given a distinguishing version
number. If the Program specifies a version number of this License
which applies to it and "any later version", you have the option of
following the terms and conditions either of that version or of any
later version published by the Free Software Foundation. If the
Program does not specify a version number of this License, you
may choose any version ever published by the Free Software
Foundation."
So the only problem would be software that specifically says "GPL
version *2*". For the Sage source code itself, we always just write
# Distributed under the terms of the GNU General Public License (GPL)
except in the following files:
interfaces/matlab.py:
matrix/matrix.pyx:
matrix/matrix0.pyx:
matrix/matrix1.pyx:
matrix/matrix2.pyx:
matrix/strassen.pyx:
I hold the copyright on all those files above.
However, in the COPYING file for Sage itself, I wrote: "All original
SAGE code is distributed under the terms of the GNU General Public
License *Version 2*."
Just out of curiosity, would anybody be angry if I were to remove the
words "*Version 2*" from the above sentence in the COPYING file?
Evidently nobody (but me) has ever actually submitted any code to Sage where
they explicitly put "Version 2" in their copyright statement.
I'm asking this mainly to see what our options are.
Regarding Sage dependencies:
* PARI -- they include the GPLv2 in the distribution, but the source code
files all just say: "you can redistribute it and/or modify it under the
terms of the GNU General Public License", i.e., nothing about V2.
So evidently PARI isn't a problem.
* Singular -- same as SAGE -- all source files say "GPL version 2 or
latter" or don't
mention anything about versions. The top-level copying file does very
explicitly say "( version 2 of the License );"
* clisp -- a cursory glance and it seems the same as Sage and Singular --
the top level COPYRIGHT file explicitly says GPL v2, but when you look
at sources, if they have a copyright statement it (here I didn't check
everything) says "v2 or later".
I'm not checking anymore right now, since perhaps the above is enough
of a sample to spark some useful discussion.
William
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