helplog.3: filesize largest 64bit

Nelson Zarate wrote on Jan 05, 2005

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NUMBER:	3
KEYWORDS: filesize largest 64bit	
DATE:	Wed Jan  5 10:47:47 MST 2005
FROM:	zarate

Q:
I'm working with some large images (1-2 GB), and IRAF has a problem with
this. Any tool I try to run gives me the message:

ERROR: Attempt to write out of bounds on file
(shoofly.astro.Vi!/net/ultrafly.old/jc4qn/iraf/scans/full_scans/img8neg.fits_)

This is an example from an 'imarith' attempt, but it seems to happen with
all tools. It seems to me that IRAF isn't allocating enough memory in
some sort of buffer to be able to work with the images. Does this sound
correct? And if so, do you know how I can fix it?

I'm running this on a UNIX system (Solaris 8) with 4 GB of RAM, running
IRAF version 2.12.2a. Let me know if you need any more info.

Thanks-

A:
 Iraf file size is limited to the 32 bit range which
 is about 2GB. When an IRAF task like imarith opens an
 input image and tries to creates another one near this
 limit you migth get this kind of problems. The same
 limitation applies to memory requirements of a task.

 To find out if this is your problem, you could you
 can operate on a subsection of the big image and see if it
 goes to completion.

 Please let us know if you have more questions.

 Nelson Zarate
 NOAO/Iraf

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Last post on Jan 05, 2005