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Re: normalized ALF (Assotiated Legendre Function)
From: |
Marco Caliari |
Subject: |
Re: normalized ALF (Assotiated Legendre Function) |
Date: |
Wed, 13 Feb 2008 15:58:25 +0100 (CET) |
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
- Re: normalized ALF (Assotiated Legendre Function), (continued)
- Re: normalized ALF (Assotiated Legendre Function), Ben Abbott, 2008/02/12
- Re: normalized ALF (Assotiated Legendre Function), Marco Caliari, 2008/02/12
- Re: normalized ALF (Assotiated Legendre Function), Marco Caliari, 2008/02/12
- Re: normalized ALF (Assotiated Legendre Function), Ben Abbott, 2008/02/12
- Re: normalized ALF (Assotiated Legendre Function), Ben Abbott, 2008/02/12
- Re: normalized ALF (Assotiated Legendre Function), Ben Abbott, 2008/02/12
- Re: normalized ALF (Assotiated Legendre Function), Marco Caliari, 2008/02/13
- Re: normalized ALF (Assotiated Legendre Function), Ben Abbott, 2008/02/13
- Re: normalized ALF (Assotiated Legendre Function), Marco Caliari, 2008/02/13
- Re: normalized ALF (Assotiated Legendre Function), Ben Abbott, 2008/02/13
- Re: normalized ALF (Assotiated Legendre Function),
Marco Caliari <=
- Re: normalized ALF (Assotiated Legendre Function), Ben Abbott, 2008/02/13
- Re: normalized ALF (Assotiated Legendre Function), Ben Abbott, 2008/02/13
- Re: normalized ALF (Assotiated Legendre Function), Marco Caliari, 2008/02/14
- Re: normalized ALF (Assotiated Legendre Function), Ben Abbott, 2008/02/14
- Re: normalized ALF (Assotiated Legendre Function), Marco Caliari, 2008/02/12
- Re: normalized ALF (Assotiated Legendre Function), Ben Abbott, 2008/02/12