Re: The Guile license and the use of LGPL libs (like GMP).

[cwitty@newtonlabs.com (Carl R. Witty)]

Rob Browning <rlb@defaultvalue.org> writes:

> Not for all purposes -- depends on what your goals are -- if we want a
> full numeric tower that's *fast* on multiple platforms, my impression
> is we may be better leaving that to numeric experts like the people
> working on GMP.

You might want to run some benchmarks before you decide on GMP.  My
impression (from the last time I looked at the issue, maybe a couple
of years ago) is that GMP is intended to be asymptotically fast on
large numbers, but that it's not particularly fast on smaller
numbers.  (For instance, you certainly wouldn't want to get rid of
fixnums and use GMP numbers for all numbers; when I looked at it, GMP
had no optimization for small numbers at all, so computing something
like 2*2 would take about 6 function calls and several loops.)

Does anybody have any idea what distribution of numbers is typical in
programs with bignums?  For instance, are most numbers that are bigger
than 32 bits in the 32 to 64 bit range, or are there lots of numbers
with hundreds of bits?  (I don't suppose anybody really knows the
answer to this question, but you'll have to make a guess before you
can decide whether one implementation is faster than another.)

Carl Witty

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