Below is a simple TI-85 program which returns the horizontal size, vertical size and screen compression ratio for the current graphing window. This is useful to give a quick idea of how much distortion is in the graph. For more discussion of aspect ratios and distortion see the aspect ratio and screen compression ratio page.

PROGRAM:ASPECT
:xMax-xMin->xSize
:Disp "window width =",xSize
:yMax-yMin->ySize
:Disp "window height =",ySize
:Disp "compression ratio =",(1.69970674487*ySize)/xSize

The need for the factor of 1.69970674487 in this program is directly attributable to the fact that both the TI-85 screen and its individual pixels are rectangular rather than square. Other graphing calculators will have slightly different factors that will need to be entered here to compensate correctly. See the graphics display screen page for more information.

This document was created in September, 1996 
and last revised on August 15, 1998.