Mathematica Disagreement between Mathematica 5, 6 and 7 ?

[Dohste]

Disagreement between Mathematica 5, 6 and 7! ??

Hey

I've got a piece of Mathematica code which I'm working on that appears to behave differently depending on which version of Mathematica it's run on...

I've tried it on versions 5, 6 and 7 and running the exact same program with the exact same input data provides different results. And I mean completely different results - not just minor variations or something.

Mathematica did its standard scan for compatibility issues and I ran it once with the suggested changes and once without them but that made absolutely no difference.

Has anyone else experienced this before?
Is there some particular type of function that the different versions interpret differently?

Appreciate any ideas!

 

[Dohste]

After working through the code again I'm fairly sure that this must be an issue with how the various versions handle inversing a matrix... ?

 

[Dale]

I have had situations where a function was no longer supported, but not like what you describe. I would not think that inverting a matrix would be significantly different unless the matrix itself were ill-conditioned. I would calculate the condition number of the matrix to see.