get_coupling_matrix for NmtWorkspaceFlat

[xzackli]

It looks like the flat workspace is missing the counterpart to

NaMaster/pymaster/workspaces.py

Line 102 in 1c0371d

def get_coupling_matrix(self):

which may be helpful for demonstrations.

[martinjameswhite]

There also does not appear to be a flat-sky equivalent to the very useful "get_bandpower_windows" method of the full-sky workspace.

[damonge]

Right, @xzackli @martinjameswhite , good point. The trouble here is that the "true" space in flat sky is a continuum (unlike on the sphere, where multipoles are discrete), so one would need to come up with a reasonable sampling rate for ell. Because of this, and because at the time no one seemed interested in having these, I never got around to implementing any of these functions.

I could pick a sampling (e.g. delta_ell = 2pi/L_max for the map in question) or (perhaps more complicated), this could be decided by the user. Thoughts?

[martinjameswhite]

From my perspective the most common use for a bandpower window function is that I multiply some "theory" Cell by the window to get the "observed" Cobs. In this case I'd want to get out an Nband x Nellmax matrix with integer spaced ells. I agree this isn't as cleanly defined as in the spherical sky case, but that would be my suggestion.