iraf.net

NUMBER:	539
MODULE:	ccmap, ccsetwcs, msctpeak
SYSTEM:	-V2.12.2a
DATE:	Tue Aug 31 09:24:53 MST 2004
FROM:	valdes

BUG:	The code which updates image headers with a TNX/ZPX WCS solution
	produced by CCMAP could fail so that evaluation of coordinates from
	the image would not be correct or agree with CCTRAN.  The failure
	is more likely to occur with small pixel scales and higher order
	distortion functions.  The problem is due to an incorrect check for
	a singular matrix when determining the TNX coefficients for the
	header.  When the code decides the matrix is singular, coefficients
	are set to zero and the evaluation is wrong.  Since this either
	happens or doesn't happen it means that there is no problem with
	accuracy until the bug is triggered.  The problem is in the GSURFIT
	math library which could also affect other tasks built on it,
	though no problems related to it are known currently.

STATUS:	The bug was identified and fixed in the math library.