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Re: FITS IO Problem [message #70666 is a reply to message #70664]

Fri, 23 April 2010 14:13

wlandsman
Messages: 743
Registered: June 2000

Senior Member

One possiblity is that you have an incompatible versions of mrdfits
and fxposit.pro (a procedure it calls to open the FITS file).
mrdfits.pro was modified in March 2009 to OPENR the file with the /
SWAP_IF_LITTLE keyword, rather than explcitly performing the byte
swapping. (This provides a significant speed improvement.)
However, if you have a new version of mrdfits.pro but an old version
of fxposit.pro then the byte swapping would not be perfomed, leading
to nonsensical values such as you describe. (I'm not sure why the
first row would be OK, though)

If that is not the problem, then the next step is to figure out
whether the culprit is mrdfits.pro or mwrfits.pro. Can other FITS
I/O programs read the file created by mwrfits.pro?

--Wayne

On Apr 23, 4:30 pm, John B <bochan...@gmail.com> wrote:
> Hi All,
>
> I am writing an anonymous structure (52 columns by 21 rows) out to a
> FITS file, using mwrfits.pro from the astrolib library. When I take
> that file and read it back in (from the same machine), I get garbage
> values throughout the
> structure. Nans, infs and just random longs... very confusing.
> Neither program complains, and until now, both have worked
> spectacularly.
>
> I have noticed that the first row is preserved properly, and that I
> can isolate a single row and write it out, then read it in, and it is
> ok.
>
> Any suggestions??
>
> Thank you!

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[Message index]

		Re: FITS IO Problem By: John B on Mon, 26 April 2010 15:52
		Re: FITS IO Problem By: John B on Sun, 25 April 2010 09:37
		Re: FITS IO Problem By: Craig Markwardt on Sat, 24 April 2010 13:08
		Re: FITS IO Problem By: John B on Sat, 24 April 2010 06:18
		Re: FITS IO Problem By: wlandsman on Sat, 24 April 2010 05:09
		Re: FITS IO Problem By: John B on Fri, 23 April 2010 20:05
		Re: FITS IO Problem By: wlandsman on Fri, 23 April 2010 14:13
		Re: FITS IO Problem By: m_schellens on Mon, 21 June 2010 01:59

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