The following applet approximates the net area between the x-axis and the curve y=f(x) for a ≤ x ≤ b using Riemann Sums. Simply enter the function f(x), the values a, b and 0 ≤ n ≤ 10,000, the number of subintervals. You may select among Left Riemann Sums, Right Riemann Sums, the Midpoint Rule, the Trapezoidal Rule and Simpson's Rule to approximate the area.

The values a and b can be changed by simply typing a new value, such as "1.2345", "pi/2", "sqrt(5)+cos(3)", etc. You may also change these values by using the up/down arrow keys or dragging the corresponding point left or right. To move the center of the graph, simply drag any point to a new location. To label the x-axis in radians (i.e. multiples of pi), click on the graph and press "control-r". To switch back, simply press "control-r" again.

Here is a list of functions that can be used with this applet.