id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
704	Sensitivity of LM minimiser to missing data	Ian Culverwell	Ian Culverwell	"Some questions about the correct treatment of missing data in the LM solver arose during the development of the differenced bangle solver in #700.  In particular:
  1. Is masking the data via
{{{
delta_y = (y%bangle - obs%bangle) * y%weights
}}}
valid if the '''R''' matrix is non-diagonal, e.g. for refractivities;
  2. Why don't we need to mask the K matrix fore refrac and bangle, so that parts of it relating to missing obs make no contribution to the error matrix '''A''', as we needed to do for differenced bending angles in order to get a match to the original source code, thus:
{{{
  DO i = 1, nstate
    K(:, i) = K(:, i) * y%weights(:)
  ENDDO
}}}
This ticket is the place to record the results of investigations."	task	new	normal	12.0	ropp_1dvar	11.0		electron density