Produces stereoscopic graphs of mathematical functions. It also stereographs approximations to the 1st and 2nd order partial derivatives. Most people are able to view them without any paraphernalia. Stereographs are pairs of stereoscopic graphs that, when properly viewed, give a true three-dimensional effect. True depth perception is due to binocular vision, and the usual single view of a surface, space curve or scatter diagram is unable to provide it, but the Stereographer does provide this fascinating 3-D sensation. You can rotate and translate the surface or space curve, zoom in or out, pan, etc.