Riemann sum calculator
This applet computes left-endpoint, right-endpoint, and midpoint Riemann sums for a given function.
You can change the function using the input box.
To allow for comparison, it displays the actual value of the integral, as well as the approximation given by the Riemann sum.
You can adjust the left and right endpoints (a and b) by using the sliders, or dragging the points themselves.
The slider n sets the number of rectangles in the Riemann sum.
The "shift" slider lets you change between left endpoint, midpoint, and right endpoint.