Error 15 and a new question...

[Timothy Hall]

I have had this error for several different reasons.  If I remember correctly,
one of my bugs that caused this to happen was when a transformation or
loadmatrix resulted with NaN as an element of the top matrix in the matrix
stack.  I think a second bug was pushing the matrix stack too many times.
Good luck, it's tough to debug when you keep ending up at the login prompt
and no corefile has been left! (I did this on a 240 with 3.1F)

While I'm here.....I have this bizarre bug that causes the lighting on 
our SGI to go into twinkie zone.  Under a few certain transformations
my light source shows up in the wrong place and shades p-gons with an "all or 
nothing" effect - either pure white or ambient grey at the verticies.  Even
more bizarre is that with shademodel( FLAT ) I will still get color
interpolation across a surface.  I must say that I've been talking to someone
at the hotline about this and he has been most helpful.

-Tim
tjh at bu-pub.bu.edu