[Radiance-general] Deterministic calculations with Radiance

[Christopher Kings-Lynne]

> Yes, I could see doing this.  We would of course be accepting 
> differences between versions and machines to some tolerance, but it 
> should be sufficient for spotting any major regressions in the code or 
> between releases.  The trick then is to have enough well-designed test 
> scenes to cover all of the basic and some of the more esoteric features 
> of Radiance.  (The "prism" and "BRTDfunc" primitives spring to mind.)

I am a developer on the PostgreSQL database, and we have a full suite of 
regression tests.  We use diff to compare actual vs. expected results. 
Perhaps we could borrow that code.

We have per-platform floating point files that we need to use to allow 
for differences in IEEE implementation between some platforms.  ie. -0, etc.

I was personally thinking for my own project checking that as I make 
changes to this big script I have, I don't affect other stuff.  However, 
having a regression suite for Radiance seems like something that's way 
overdue for a piece of software that needs to be correct for legal 
purposes :)

Chris