[daip] BPASSPRM(4) in BPASS/CPASS

[Lynn D. Matthews]

Thanks for the update on SNSMO. I am afraid that I already have another
question, this time about BPASS/CPASS.

My understanding is that when BPASSPRM(4)=1 in CPASS or BPASS, this is
supposed to indicate that only the complex phases will be written to the
BP table and the amplitudes will be set to unity. I am trying to use
this in a case where I have already solved for the amplitudes using
autocorrelation data.

In practice, when one invokes this option in BPASS, the "Real" column of
the BP table ends up with values close to 1, but with considerable noise.
Noise is then introduced in the amplitudes when one applies the BP
table.

In the CPASS case, if one solves for A/P (i.e., CPARM(5)=2), there end up
being small wiggles in the amplitude that are usually minuscule, but these
can be several per cent if the phases were noisy.

Am I misusing BPASSPRM(4)? Or is this behavior somehow inevitable given
the way the programs treat Re/Im versus A/P?

Thanks,
Lynn