nderiv
Numerical differentiation of a real function of one real variable.
yp=nderiv(func, v)
Inputs 
func 
A function object representing a function of the form y=f(x) which returns the value of the function whose derivative is to be
calculated.

v 
The value of x at which the derivative is required. 
Outputs 
yp 
The derivative of the specified function with respect to the argument value at v .

Description
nderiv
uses a four point numerical differentiation formula.
Example>>nderiv(@(x)sin(x),pi/4)
0.7071
>>nderiv(@(x)sin(x^2+3x+2)*x,pi/4)
0.0411