implementing numerical derivative

Jan 4 2011 12:24 PM

Hi!

I would like to implement a numerical derivatives, but i dont know how to?

Can you please help me? I have searched on the web, but I didnt found any algorithms..

The input would be something like this: (function, point,step)

Example: f(x) = -0.1x^4 - 0.15x^3 - 0.5x^2 - 0.25x + 1.2
at x = 0.5 and step = 0.5

Thanks!