Quote from Corey:
There are plenty of available packages for scientific computing in Ruby. The ones that spring to mind are the gsl bindings (ruby-gsl), statistics2, R bindings (ruby-rmathlib or rsruby), LAPACK bindings, libsvm bindings (RubySVM), etc...
Let me give you an example of how I used Ruby lately: I had about 20 years worth of historical fundamental company information on 300+ companies. It was pretty much quarterly information. First, I needed to parse all the files that the data was in and load it into a database. The ActiveRecord library made this easy -- and migrations made database maintenance even easier. Then, I had to run some analysis on the data -- analysis that would take a long time no matter what language you were using. But using Amazon's EC2 platform and distributed Ruby (DRb), I was able to quickly analyze the data by making the process parallel.
Could I have done this all in C++ or Java? I am sure I could have. But I bet that I would have had to have written a lot more code to get the task done. To me, I was willing to waste the extra CPU cycles for the sake of programmer ease...
Again, this is MY experience. I find Ruby useful. I also find it to be a pleasure to program in. Each tool in its place, as I continue to say. There is more than one way to skin the cat -- and LuaJIT is a very valid option. I just happen to find that Ruby works for me.