GalSim-developers/GalSim — Issue #9: removal of NR gaussjinv from meas_shapes_hsm psfcorr.c
Author: rmandelb
Created: 2012-02-28 04:31:23+00:00
State: open

Currently the meas_shapes_hsm code relies on one NR routine, gaussjinv. (There are several NR codes in there that are officially open-source, such as dvector, ivector, dmatrix, etc. - those don't have to be removed, though we may wish to later on.) We should make the code use TMV for matrix inversion instead of gaussjinv; the result is that the code will probably be faster, anyway.

Please note: the ONLY place that the code requires gaussjinv is for the shapelets PSF correction, which is only one of several possible methods. If there is no clear and simple way to do this using TMV, we should simply remove gaussjinv and live without a shapelets PSF correction (the implementation in this code was not, in any case, very well tested, since we never used it for science!). This would be preferable in my opinion to someone spending a lot of time on getting this to work with TMV. Opinions on just how hard this replacement of gaussjinv --> TMV would be are therefore valuable!

If we choose to replace gaussjinv with something from TMV, this is probably a job for Mike. If we choose to rip it out and not have PSF correction via shapelets from this code, then this is a job for Rachel.