From the project README:
== Description

ALPHA - ALPHA - ALPHA

GSL4r
Ruby GNU Scientific Library via FFI

The Foreign Function Interface allows for run-time bindings
to shared libraries. Using FFI to interface between Ruby and
other libraries written in other languages makes these
libraries runnable across all Ruby interpreters that have FFI
capabilties (MRI, JRuby, etc...).

This avoids the complications with implementation specific C
extensions or Java Native Interfaces in the case of JRuby.

== Documentation

This project is currently in its alpha stages and as of
22 Mar 2010, I have only pushed a library for using Complex
functions in GSL, all constants are defined, and handling
pointers to blocks and vectors and basic vector functions.

This library is also designed to be self testing and does
so by generating automatic tests that compare results against
the answers returned by actual C calls to the GSL library
against the FFI wrappered ruby calls.

For more information about the automated tests, see:

http://shrewdraven.com/content/automatic-generation-tests-gsl4r

These tests cover the complex routines as well as the
vector routines so far.

== Getting Started

Right now you can look at the existing project by cloning the
GIT repository via:

git clone git://rubyforge.org/gsl4r.git

== Installing gsl4r

gem install -r gsl4r

== Examples

Also see the examples directory in the gem.

cd gsl4r/lib
irb -r rubygems -r gsl4r -r gsl4r/complex
irb(main):001:0> include GSL4r::Complex
=> Object
irb(main):004:0> a=GSL_Complex.create(1,1)
=> (1.0,1.0)
irb(main):005:0> b=GSL_Complex.create(2,2)
irb(main):009:0> a.abs
=> 1.4142135623731
irb(main):012:0> b.add(a)
=> (3.0,3.0)
irb(main):013:0> a.logabs
=> 0.346573590279973
irb(main):014:0> a.gsl_complex_logabs
=> 0.346573590279973
irb(main):016:0> include GSL4r::Complex::Methods
=> Object
irb(main):015:0> gsl_complex_add(a,b)
=> (3.0,3.0)
...
irb(main):010:0> require 'gsl4r/const'
=> true
irb(main):011:0> include GSL4r::PhysicalConstants
=> Object
irb(main):013:0> p CGS::JOULE
10000000.0
irb(main):014:0> p MKS::ERG
1.0e-07
...
irb -r rubygems -r gsl4r -r gsl4r/vector
irb(main):001:0> include GSL4r::Vector
=> Object
irb(main):002:0> a=GSL_Vector.create(3)
=> #
irb(main):003:0> b=GSL_Vector.create(3)
=> #
irb(main):004:0> a.set_with_array([1,2,3])
=> #
irb(main):005:0> b.set_with_array([4,5,6])
=> #
irb(main):006:0> a.mul(b)
=> 0
irb(main):012:0> a.values
=> [4.0, 10.0, 18.0]
...

== Questions and/or Comments

Feel free to email
{Colby Gutierrez-Kraybill}[mailto:colby@astro.berkeley.edu]
with any questions.

== Copyright

See LICENSE and LICENSE.LPGLv3