Okay, so I was writing a program to display the Mandelbrot set and for some reason my Y user variable was switching from 1 to 0 for no good reason. After countless minutes of furious debugging, I isolated the cause to an innocuous Pt-On( command. For some reason these commands:
:-2.5→XMin :1→XMax :1→YMax :-1→YMin :-2.5→X :1→Y :Pt-On(X,Y
will draw a point at (-2.5,1) as you'd expect, but at the Pt-On( command, Y is changed from 1 to 0. I tried with different window values, and it worked with some and not others. Finally, I decided to use L instead of Y as my variable name, and it worked perfectly.
I assume this is some weird corner case due to an oddity of the calculator. Has anyone ever encountered this before? Does anyone knowledgeable about this sort of thing know the reason?