Pol rotation broken for TE/EE only runs

[adrien-laposta]

Hi @cmbant @mgerbino

I am using MFLike in the context of a TE/EE only run. The list of requested_cls is then ['te', 'ee'].
If we set polarization rotation systematic parameters alpha_{exp} different from zero, the code will try running L627 in mflike.py.

It results in a KeyError, requesting a missing 'tt' key. I suspect this is coming from the syslibrary module, and in particular from the syslib_mflike.Rotation_alm class. The associated eval method requests for the TT power spectrum in self.cl.

A quick fix would be to add some checks to ensure that the requested power spectrum is in the cls list passed as an argument.

[mgerbino]

Hi @adrien-laposta , thanks for pointing this out! Yes, I see the point. The current implementation implicitly assumes that you run the full TTTEEE and that you may want to complement it with BBEBTB (i.e., it does not include the possibility to run without TT or with some other spectrum combinations). As you suggest, the quickest solution is to add a check similar to, e.g, line 114, while thinking of a more general prescription.