comp.lang.idl-pvwave archive: archive » IDL is not accurate enough!

Home » Public Forums » archive » IDL is not accurate enough!

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: IDL is not accurate enough! [message #62299 is a reply to message #62192]

Tue, 02 September 2008 05:20

Haje Korth
Messages: 651
Registered: May 1997

Senior Member

Noah,
other in this thread have laid out the issue, nothing to add here. If you
want to go brute force with extended precision, check out the cephes math
library at http://www.netlib.org/cephes/. There is an extended precision
version that has a gamma function. I have used that in the past for
calculating hypergeometric functions and it served my needs. I used
call_external, but you can certainly turn this into a dlm.

Cheers,
Haje

<noahh.schwartz@gmail.com> wrote in message
news:c7b7fc70-b4db-4c3d-8d2b-50f88dbd1d62@s50g2000hsb.google groups.com...
> Hi,
>
> I've been having problems with IDL accuracy. I'm trying to perform
> calculations using the gamma function. The problem is that it grows
> VERY fast! Performing this calculation in double (namely gamma(x)/
> gamma(y) with x and y big) yields the result: NaN...
> Would it be possible to use a program like 'Mathematica' (or any
> other) and to plug it in my ILD program? Some kind of CALL_EXTERNAL
> that is to say. If it is possible, how can I do it and what is the
> best program to use?
>
> Thanks,
> Noah

Report message to a moderator

[Message index]

		IDL is not accurate enough! By: noahh.schwartz on Thu, 28 August 2008 09:30
		Re: IDL is not accurate enough! By: Haje Korth on Tue, 02 September 2008 05:20
		Re: IDL is not accurate enough! By: Kenneth P. Bowman on Fri, 05 September 2008 09:53
		Re: IDL is not accurate enough! By: MP on Fri, 05 September 2008 09:18
		Re: IDL is not accurate enough! By: Michael Galloy on Fri, 05 September 2008 08:57
		Re: IDL is not accurate enough! By: Kenneth P. Bowman on Thu, 04 September 2008 13:33
		Re: IDL is not accurate enough! By: pgrigis on Thu, 11 September 2008 07:44
		Re: IDL is not accurate enough! By: noahh.schwartz on Mon, 15 September 2008 02:37
		Re: IDL is not accurate enough! By: pgrigis on Thu, 11 September 2008 07:35
		Re: IDL is not accurate enough! By: pgrigis on Mon, 15 September 2008 06:40

Previous Topic:	Re: Maximum index for arrays?
Next Topic:	Re: IDL calls C calls IDL?

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Sun Oct 12 04:42:17 PDT 2025

Total time taken to generate the page: 1.36496 seconds