[fpc-pascal] math with infinity and NaN

[Marco van de Voort]

In our previous episode, C Western said:
> > I can do things like +infinity*2 and +infinity-3 and even sqr(infinity) 
> > and power(infinity,10) the results are still +Inf which is expected? 
> >  ??but I can?t do anything involving subtracting infinity from 
> > infinity.? 

Isn't that normal? Otherwise, what would inf+inf-inf be if you know that
(inf+inf) =inf