[Radiance-general] Divide by zero in luminaire model / brightdata

[Randolph M. Fritz]

I'm getting the following error messages from a luminaire model:
  rpict: warning - compute error for brightdata "luminaire_pendant3_CB087_dist"
  rpict: Division by zero

I'm going to dig into this further - I didn't build the model, and 
there may be something really obvious wrong with it - but I was 
wondering if anyone has seen anything like it, and has any tips.
-- 
Randolph M. Fritz