OPTSCL -- scales images to reach minimum Chi**2
This routine should be run immediately after a fake image has been set
up, and prior to running 'memit'. Its purpose is to correct for a poor
choice of initial image. The reason is that inside 'memit' the image is
only allowed to change by a small fraction each iterattion and if it
is far out the first iterations are spent just trying to get the scaling
right. This can be done much more quickly with 'optscl' because it is
just a linear least-squares problem.
Parameters:
IMAGE -- Image to optimise
DATA -- Data file containing data and errors which will be used
to rescale the image.
GLOBAL -- TRUE then a single parameter is optimised for all the images.
FALSE then each image is separately re-scaled. If there
is only one wavelength then GLOBAL = TRUE automatically.
If you can you should first try separate rescaling (GLOBAL
= FALSE) which gives the lowest chi**2. However it can also
produce negative scalings which are rejected because
they cannot be handled by 'memit'. If this happens then
rerun with GLOBAL = TRUE.
This command belongs to the class: extra