Re: normalized ALF (Assotiated Legendre Function)

[Marco Caliari]

I discovered that the warning is misleading. Consider

legendre(151,0)

The last entry is -Inf and the script "should" returns a warning (you 
should replace scale == inf with abs(scale) == inf). But, there is no 
instability: the value -Inf is "right", in the sense that it is too large 
in magnitude to be represented. Now consider

legendre(151,eps)

Again a warning (due to the check on a and b), but, again, no instability.

Moreover, Matlab has no warnings and it is less robust. Consider

legendre(151,-0.9)

in Matlab and with the script now enclosed. To conclude, I would suggest 
to leave the warnings out.

Marco

> On Feb 13, 2008, at 8:16 AM, Marco Caliari wrote:
>
> > > That line was incorporated from your version. Should it be something else?
> >
> > Something like that to be added:
> >
> > if (max(abs(scale)) == Inf)
> > underflow = true;
> > endif
>
> ok.
>
> How about the attached?
>
> We still need some tests added for  higher orders. I'll get around to that 
> latter today.
>
> Ben

legendre.m
Description: Text document