normalized ALF (Assotiated Legendre Function)

[Marco Caliari]

Hi Ben.

This one still gives problems

legendre(151,0)

with an Inf. I would check the line

scale = -scale * (2*m-1);

and try to prevent that scale becomes Inf.
Moreover, I don't understand the limit 255 on n. With the normalizations, 
there are no problems for n>255.

Best regards,

Marco

On Tue, 12 Feb 2008, Ben Abbott wrote:

> I've added a check for underflow. This is my first time doing such, so I may 
> be quite off on what is commonly accepted as proper.
>
> The method I used detects an underflow for orders greater than 151.
>
> 	octave:104> result_octave1 = legendre  (152, [-1:0.1:1]);
> 	warning: legendre: results may be  unstable for high orders.
>
> I've attached the script.
>
> Ben
>