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Re: TRIGRID problem
- Subject: Re: TRIGRID problem
- From: davidf(at)dfanning.com (David Fanning)
- Date: Fri, 5 Jan 2001 13:30:11 -0700
- Newsgroups: comp.lang.idl-pvwave
- Organization: Fanning Software Consulting
- References: <3A56172A.E82F777B@cdc.noaa.gov>
- Xref: news.doit.wisc.edu comp.lang.idl-pvwave:22837
Cathy Smith (firstname.lastname@example.org) writes:
> I ran into a problem using TRIGRID to interpolate an array from 36x16 to 72x16
> on a sphere. I have the two lines
> This did not work and gave me the error
> % TRIGRID: Points are co-linear, no solution.
> However, using 354.99 instead of 355 gave me the correctly interpolated
> grid and no error.
> I think I followed the directions correctly (and in fact I tried setting
> GS to 5x5 and other similar
> permutations but got the same error).
> Does anyone know why?
I'm going to guess the infamous round-off error
related to the way computers store numbers. But
this is a useful trick to work around this frequent
problem. I've tried scaling the data before gridding,
etc. Lot's of things work. Sorta. :-)
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: email@example.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155