if you want to see a mathematical function diagram, this class is written for you!
this class gets some parameters and shows the desired function diagram in jpeg-
format. if you want, you can save that image by right clicking on it(like all 
images on internet) .
i have created a form for this class. just run index.html file.

NOTE: you must have GD installed to use this class .(enable GD2 extension
in you php.ini file .)
NOTE: f(x) must be written in php sysntax :
ex: sin(2*x); 
ex: x*x;
ex: 2*x*x+3*x+1; and ...
Reza Salehi