Built-in function for Differentiation:

The MATLAB has a built-in function, diff that returns the differences between consecutive elements in a vector. For illustration,

>> diff([4 7 15 32])

ans =

3 8 17

For a function y = f(x) here x is a vector, and the values of f  '(x) can be approximated as diff(y) divided by diff(x). For illustration, the earlier equation can be written as an anonymous function.

>> f = @ (x) x .^ 3 + 2 .* x .^ 2 - 4 .* x + 3;

>> x = 1:3;

>> y = f(x)

y =

2 11 36

>> diff(y)

ans =

   9 25

>> diff(x)

ans =

   1 1

>> diff(y) ./ diff(x)

ans =

9 25