iraf.net

Greetings,I have noticed some irregularities in running the iraf task "imshift"
after upgrading my desktop, running rh9, from PC-IRAF V2.12.1-EXPORT to
V2.12.2a-EXPORT. Using the same input parameters within "imshift" on
the same input file, the output file produced after this upgrade is
noticably different. (the input file is shifted differently) I have
reinstalled V2.12.1 back onto this desktop, and can reproduce my
original results (different than that produced on the V2.12.2a version).I have further explored running this task with the same input parameters
(on the same input file) on different versions of iraf loaded on
different machines...and have found:a) rh9 machine running v2.12.1-export; sun machine running v2.11.3; IRIX
machine running v2.11.3 all yield the same resultsb) rh9 machine running v2.12.2a-export; fedora core 2 machine running
v2.12.2a-export yield the same results...which are different than that
found in a)
Have other users reported this anomaly when using v2.12.2a - and do you
have any idea what may be causing the problems described?Thanks in advance for your help,John Wisniewski

Hi John,
What's the definition of "different" in this case? Following the
V2.12.1 release the task was modified to use double precision to fix a
bug where the specified shift was less than the precision of a real, but
otherwise the task is unchanged. Are the differences within the machine
precision or are we talking about major differences?
Regards,
Mike Fitzpatrick