In some cases, each iteration can add a fixed constant " error map" into the astronomical map, which accumulates with each subsequent iteration, preventing convergence and causing strong large-scale structures to appear in the final map (typically ripples on the scale of the FLT filter). This parameter attempts to counteract this by allowing a map to be specified which will be subtracted from the astronomical map at the end of each iteration. At present, the dimensions of this map must be identical to those of the real map. See also parameter "epsout" . [$<$undef$>$]

MAKEMAP, CALCQU