Heya,
On Mon 26 Jul 2010 23:01, Andreas Rottmann <a.rottm...@gmx.at> writes:
> scheme@(guile-user)> (random (ash 1 32))
> ERROR: In procedure random:
> ERROR: Argument 1 out of range: 4294967296
Well, it's not a segfault at least :)
The point of that change was to indicate that the RNG did not return
sizeof(unsigned long) bits of randomness; it always returned 32
bits. See the note in "BSD Random Number Functions" in libc's manual:
*NB:* Temporarily this function was defined to return a `int32_t'
value to indicate that the return value always contains 32 bits
even if `long int' is wider. The standard demands it differently.
Users must always be aware of the 32-bit limitation, though.
I'll fix this now to avoid the error, but there is still work to do on
the RNG -- we really need to update the RNG, I think. Brian Gough, the
GSL maintainer, says MT19937 is the one to use, and specifically the new
SIMD version at
http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/SFMT/index.html. We
should replace our MWC RNG with that one.
Would you be interested in doing this? We would need some test
suites too, I think, and possibly changes to the scm_t_rng structure.
Cheers,
Andy
--
http://wingolog.org/
