This page demonstrates a java applet. This is a program, written in the java programming language, that is transfered to your browser when you load the page Ap.html. Your browser does all the calculations needed to evaluate the expression at the specified value of x.
Only a few browsers are java-enabled, but most seem to claim that they will support java in the near future.Enter the formula you want to evaluate (using x as a variable) then assign a value to x and hit the "calculate" button.
In defining f(x) you can use these functions: sin, cos, tan, exp, log, atan, asin, acos, sqrt, abs.