You can enter your own function or use one on the menu, in the top white space. The lower and upper limits of integration are entered in the next two spaces. The scale used to display your function are defined by lower and upper limits that you can enter on the next pair of spaces.

The applet calculates an approximation to the integral of your function between the given limits of integration, by dividing the region between those limits into strips, and applying each of the four approximation rules in each strip. The slider determines the number of strips, which increase as it moves to the right. The four methods are: use left hand y value for each strip, use right hand value instead, use the average of the two (This is called the trapezoid rule) and Simpson’s Rule. Simpson’s rule when there are an even number of strips, can be described as taking 4/3 of the trapezoid rule answer, and subtracting 1/3 of the trapezoid rule with half the number of strips.
If you click in either of the circles with arrows in them, the slider moves by one in the indicated direction.

This tool uses JQWidgets extensively. Please verify their copyright.

Developed by Daniel Kleitman and Jean-Michel Claus.