Any programmers here?

[Arcade Fire]

For my work I quite often have to write 'quick and dirty' programs to find answers to questions that would take me too long to calculate by hand, and to which there's no existing program which does the job I need. Typically these take < 1 hour for me to write and debug, and I don't use them much after I've got the answer that I need from them.

I'm currently doing this in MATLAB, which is good in that it's easy to use, but bad in that the calculations that I need to do are getting slowly more complicated, and MATLAB is really slow. So I need to pick up another language.

I've used C before, and it seems powerful and fast, which is what I require. Before I delve into learning it, though, can anyone recommend any languages that are:

(a) Relatively easy to learn for someone with a little (but not much) programming knowledge,
(b) Have a syntax which is simple enough to write quick and dirty programs in not a great deal of time,
(c) Powerful enough to perform quite complicated mathematical calculations, and
(d) Fast.

Also, any tips on how to pick up the language would be a good idea - links to good books etc. Thanks!