Valchava workshop, day four

Rix arrived in Valchava today, and (after a morning hike) proceeded to talk about making high-resolution models of multi-resolution (or heterogeneous) multi-spectral data, with the example being our dust maps made from Herschel data. One thing I learned in the discussion is that we maybe should be using L-BFGS-B optimization instead of the hacky Levenberg-Marquardt-like thing we are doing now. I was surprised, since Lev-Mar-like methods know that the problem is least-squares-like, whereas L-BFGS-B won't, but the experts (especially Dilip Krishnan) advised strongly.