The mem0 package version B in IRAF was released in October 1992. Since
then the task irme0b for image restoration by MEM in this package has
undergone major changes. The latest version of this task, with the name mem, will be included in the STSDAS V.1.3.1 patchkit scheduled
to be released in late 1993. Currently its executable code cmem.e for
Sun workstations, together with the parameter and help files, are stored in the
NOAO anonymous FTP site (iraf.noao.edu, /contrib/).
The model updating (MU) technique has greatly improved the performance of the task, temporarily named cmem, of the new version. The iterations converge much faster, and the photometric nonlinearity of the results have been reduced.
In the following we will elaborate on the MU technique and its implementation in cmem. Statistics and illustrations will be used to show the aforementioned merits.