[gnuastro-devel] [bug #55544] Arithmetic's output WCS with where operator is not as expected

[Mohammad Akhlaghi]

URL:
  <https://savannah.gnu.org/bugs/?55544>

                 Summary: Arithmetic's output WCS with where operator is not
as expected
                 Project: GNU Astronomy Utilities
            Submitted by: makhlaghi
            Submitted on: Tue 22 Jan 2019 03:12:58 PM UTC
                Category: Arithmetic
                Severity: 3 - Normal
              Item Group: Output not reasonable
                  Status: In Progress
                 Privacy: Public
             Assigned to: makhlaghi
             Open/Closed: Open
         Discussion Lock: Any

    _______________________________________________________

Details:

In the manual (version 0.8) we have mentioned that "output WCS information
will be taken from the first input image encountered". This would logically
mean the first dataset (with a WCS) that is found on the command-line. 

However, for implementation purposes (especially when there are hundreds of
files), Arithmetic doesn't immediately read a file into memory! It will keep
its reference and load it into memory only when processing is to be done on it
(and immediately freed after it is no longer necessary).

This caused confusion when the "where" operator is used, for example in a
scenario like this:

++
$ astarithmetic image1.fits --hdu=1 image2.fits --hdu=1 --output=masked.fits 1
eq nan where
--

In this scenario, while the `image1.fits' is the first one on the
command-line, `image2.fits' is the first one that is actually operated on. So
Arithmetic would load the WCS of `image2.fits' and not `image1.fits' (as
mentioned in the manual).

I am busy implementing the fix.

This bug was reported by Raúl Infante-Sainz.




    _______________________________________________________

Reply to this item at:

  <https://savannah.gnu.org/bugs/?55544>

_______________________________________________
  Message sent via Savannah
  https://savannah.gnu.org/