DESCRIPTION

IMQUADFIT is used to perform a quadratic least squares fit at each
pixel in a set of images.  The independent variable is the value of
an image header keywords; typically an exposure time.  The output
consists of three images containing the coefficients for each pixel.
Symbolically the fitting equation is

	y(i,j) = a(i,j) + b(i,j) * x + c(i,j) * x**2

where x is the independent variable, such as exposure time, and
a, b, and c are the images with values at pixel (i,j).

The application for which this task was created is to determine independent
linearity coefficients for each pixel in a detector where the independent
variable is the exposure time.  The input data consists of high quality
flat fields (averages of individual flat fields) taken at different
exposures.

INSTALLATION:

1. Copy the script to a convenient location such as your IRAF home
directory or a scripts subdirectory.

2. In your loginuser.cl or login.cl file add

	task imquadfit = <path>imquadfit.cl

where <path> would be the path to the script such as home$ or home$scripts/.

There is no help page for this script.

USAGE:	imquadfit images coefa coefb coefc keyword=<keyword>

AUTHOR:	Michael Corbin (mcorbin@as.arizona.edu)
The script was derived from a similar script by Mike Merrill (mmerrill@noao.edu)