Hi. I have a set of data representing acceleration. To get the distance I integrate twice using a summation method and looks like: accelleration: 0, 40, 30, -50,-80, -40. velocity: 0, 40, 70, 20, -60, -100. distance: 0, 40, 110, 130, 70, -30. The distance should be zero as the movement goes back to the original point so there clearly is an error. Is there a better way to get the distance. I have heard runge kutta is good for this sort of stuff but am not sure where and how to put the data in. Any suggestions to how i can sort out this error. Thanks. Mark.