Documentation without printout of a set of computer graphic routines that allow a user to enter a curve into an IBM 360/40 by tracing it on the RAND Tablet and interactively to specify various ways of fitting, editing, and displaying the curve on an IBM 2250 scope, thus visualizing the results of using certain methods in approximation theory. Routines are provided to least-squares smooth the data in various ways and to compare the results with a cubic spline (the smoothest of all twice continuously differentiable functions). The cubic spline curve, the least-squares polynomial curve, and the original handdrawn data curve may be displayed separately, together, or in pairs, with the system rescaling the axes as needed. (The HIGH SPEED SPLINE FIT mode eliminates rescaling.) Pointing the Tablet stylus at PUNCH DATA outputs a set of cards that will recreate the display at any time. To conserve storage, certain small routines are repeated under different names (e.g., ENDPT and ENDPT2) rather than overlaying them. 89 pp.