Instructions
Click the "100 Paths" buttons to display a full set of paths.
Click the "Up Paths" and "Down Paths" buttons to display a subset of paths
that contribute up and down vectors respectively to the total sum represented
by the red arrow on the right. CLick "Clear Paths" to begin with
a new set of paths. Use the "Zoom In and "Zoom Out" buttons to resize the
arrows to fit in the display window.