Is your C code one of the “well-known” open source libraries that do
this kind of computation, or is it home-grown? The reason I ask is that
there are quite a few Python interfaces to the well-known libraries, and
it would be relatively easy to port some of them to Ruby.
It is home-grown … partly because the divisions I have to do
involve several variables (see an example here:
Yahoo | Mail, Weather, Search, Politics, News, Finance, Sports & Videos) … I am not aware
that there are any “well-known” open-source libraries for this as it
seems a more exotic part of computational algebra after all.
One problem of this type of computations is that they tend to be
a.) extremely consuming in computation (twice exponential in the number
of variables … and any interesting applied problem now
involves around 20 variables or more),
so C seemed a good choice for doing the bulk of the work, but problems
of this size tend to be just unfeasible unless one can make good use of:
b.) the actual amount of computations depends on the ordering of the
terms (defined based on the different variables) and you can achieve
dramatic differences if a good procedure is found. So I am trying out
several strategies for reducing the amount of work based on the
concrete structure of the problem (graph theoretic ideas, mostly).
These things are done in Ruby, as it is so much nicer to code in
and as this is a part of the problem where speed of computation
is not so critical, as most of the computation is done in the division
process written in C.
Now, to connect the two, I looked at this tutorial:
I’ve managed to make this work without any problem.
Now, what I still do not understand is quite what SWIG does precisely
for the communication of Ruby and C.
1.) I faintly recall reading a post on this list that SWIG could be
used not only to extend Ruby with C, but also the other way round … so
thinking that maybe I could use the Ruby’s Rational to extend
my C code … if you have any pointers for extending C with Ruby, please
let me know.
2.) If you don’t have to declare variables with types in Ruby, but can
use Ruby nevertheless in connection with C via SWIG, and possibly
inversely (as said in 1.), SWIG must somehow be able to determine the
C structure of Ruby and associate the two.
Beyond the problem I’m having here, I would also like to know how
realistic this is - in the most perfect of all worlds, this would mean
one could re-use any code from any language having a C basis in
any other … just a dream, but a nagging one.
One other note – have you looked at RubyInline?
Yes, but as far as I understand it, this allows to use C as if it
were a scripting language, but it comes at a cost of speed, which I
can’t afford here.