This page demonstrates how to use a DataFilter Physlet to integrate data that is being sent from a data source to a data listener. The data source is the red ball in the EField animation. It sends its [x,y,vx,vy,t] values to all data listeners. The script makes a data connection to series 2 of the graph using t and y as the coordinate pair. This series is plotted in red. But there is a second data listener on this page. It is an Integrator Physlet contained in the Filters package. The Integrator uses the trapezoidal rule to integrate vy before passing this data on to other listeners. The Integrator data is passed to series 1 of the DataGraph. It is plotted in blue. Notice the position of the object matches the integral of the velocity to within the arbitrary integration constant.