[Ian, Lee]

Using saved versions of the models from the 300m cavity repo (https://git.ligo.org/wieldphysics/ligo300mfiltercavity) we have matched the resulting controllers from the 'ligo300mfiltercavity/T_ASC_mixed_H_BH2.py solver2' test with new buzz code (https://git.ligo.org/ian.macmillan/buzz).

The 300m result shows the mixed H2/Hinf result at one weight for the two FOMs: (BNS FOM: 250000, and the Flat FOM: 1). The multiple traces comes from the gamma parameter being decreased flattening the closed loop gain. These results (with the file prefix "300m") are in the attachments. These controllers match with the open and closed loop gain that we get from the Buzz code also in the attachments with the prefix "buzz".

I also attached two RMS Plots. The First one (with the prefix "RMS_single" is of the single FOM weighting which is the controllers we calculated in the comparison above. As is seen on the plot the phase margin diverges from zero as the gamma decreases. This is what we expect but was not what we were seeing earlier because of a bug. It may be wise not to trust 'control.margin()'.

Once we know that the result of our two codes match I wanted to explore the what other weightings did. The last plot (prefix "RMS_multi") is using a weighting of F1_gain form 250 to 250000 with 4 different weightings, where F2_gain (flat FOM) is 1/F1_gain. The results show that either the solver is very fragile or maybe I haven't picked the correct weighting. It is possible that the weighting is well out of the stable regime for the solver. This would be strange because the max F1 weighting is 250,000 which should be the most unstable weighting combo since the solver needs a non-zero D matrix. This is disappointing but one good thing is that its border seems to follow the nice optimal RMS limiting curve set by the H2 solver.