plot and calculate integral

I need to create a script that calculates and plots an integral of any function. I am not allowed to use quad, I'm supposed to replace quad I guess. I am completely lost, does anyone know what to do?

Cheers

Answer 1

[Star Strider]

Numerical integration

Answer 2

[Roger Stafford]

I wrote a routine for the File Exchange which computes a cumulative integral using cubic (third degree) approximation which you might like to use. It can be downloaded from:

   http://www.mathworks.com/matlabcentral/fileexchange/19152-cumulative-cubic-integration