[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: normalized ALF (Assotiated Legendre Function)

From: Ben Abbott
Subject: Re: normalized ALF (Assotiated Legendre Function)
Date: Mon, 11 Feb 2008 06:50:42 -0500

On Feb 11, 2008, at 3:01 AM, kruvalig wrote:

Thank's a lot for quick answer. I very suprised of it.

On Sun, 10 Feb 2008 01:37:10 +0300, Ben Abbott <address@hidden> wrote:

I've posted a patch and changelog to the maintainers list. Attached to
email is the modified script. legendre.m

Can any one test output of this file and output matlab file to high degree

  result_mlab=legendre(80,[-1:0.1:1], "norm");
  result_octave=legendre(80,[-1:0.1:1], "norm");

        warning: legendre is unstable for higher orders
        ans =  1.4343e+16

This is what I get.

Here is a file, generated in octave
by code:

  result_octave=legendre(80,[-1:0.1:1], "norm");
  save -v7 result_octave_80

I think this code
scale = (-1).^m .* sqrt ((n+0.5) .* factorial (n-m) ./ factorial (n +m));
whill give bad answer in high order of legendre.
And we have to write: To what order it compute in right.

I'm not so sure a problem lies with the normalization. When I compare results for legendre(80, [-1:0.1:1]), I get

        warning: legendre is unstable for higher orders
        ans =  5.4154e+126

I haven't looked into the details as how this function works yet. I'll do that today.

In any event, can you (someone else?) propose a change? ... or a reference for how it should be done?


reply via email to

[Prev in Thread] Current Thread [Next in Thread]