Derivative incorrect calculation

[kisdma]

The first derivative has an incorrect sign. The higher derivatives also need to be multiplied by factorial(n)*(-1)^n. Or c matrix need to be flipud'ed instead of (-1)^n (even columns are symmetric anyways).

This issue is very easy to see using the provided example with noisy sin function.

I hope this is clear - let me know please. I can incorporate these changes myself in a fork and you could merge - if you like this way better.

Anyway, thanks for this great code, author! I hope this will help to make it perfect.