The answer is yes! It is an 1e10 and not 1e-10. At 0.0 you got to pick the interval yourself. You can't just use the starting point x

Date: Wed, 1 Mar 2000 16:06:28 +0100 (MET) From: Fredrik Stenberg <su96-fst@nada.kth.se> To: Hassan Aurag <aurag@CRM.UMontreal.CA> Subject: Re: [Numpy-discussion] Derivatives MIME-Version: 1.0

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Hi,

attached is a file called Derivative.py.

It computes derivatives and is based on an algorithm found in Numerical Recipes in C.

What to do you think about it and has anyone started a "serious" calculus oriented subpackage for Numerical Python in general?

I mean: derivatives, partial derivatives, jacobian, hessian implemented fast and precise.

On another note, why isn't infinity defined in NumPy?

Why is tan(pi/2) a number even if big? Shouldn't it be infinity?

I tried your algoritm on sin(x) and i got some rather interesting results.

######### EXAMPLE############# from math import sin

def f(x): return sin(x)

import Derivative

print Derivative.Diff(f,0.0)

########RESULT################ -2.03844228853e-10

It should be approx 1.0

I found the error i think.. check row 28 in Derivative h = random()/1e-10 should that be h = random()/1e+10??

Fredrik