Add a method to compute the transfer function between two TimeSeries objects
Created by: eagoetz
Added a TimeSeries method to compute the transfer function between two TimeSeries objects; added command line functions to carry this out as well, as I thought that may be useful for, e.g., LDVW
This method follows the standard procedure to compute the unknown transfer function between two time series using the cross spectral density and power spectral density estimators. This is what DTT does see, page 20
This functionality was mentioned in #321 (closed), though perhaps not initially what Andy had in mind as he mentions ASD2, etc., and code snippet suggested by me