Returning RMSE in addition to residuals rather than printing it, and a few questions

[nicmazza]

Hi,
First of all, I love this tool, thanks to everyone who worked on it!

I have been using the package for a bit, and I was wondering if it would make sense to have the linKK return the RMSE in addition to the residuals.
This might be good as it would then possible to store all linkk rmse when doing batch fittings of files and stored in a table with the filename and other useful informations, which can be useful for example when looking back at old data to make sure the dataset was of good quality.

Then, for the questions :)
I have read the code, but I am not sure I fully understand that function (I am not the most skilled programmer :) ). It seems that it only calculates the rmse when M is a multiple of 10 and prints it out rather than returning it, which seems odd to me but I am probably not understanding either the function itself or the linkk algorithm.
I have another probably simple question: could you please explain to me the reason the residuals are returned divided by the module of Z, rather as the point by point distance between the two profiles? Maybe I am not following what the eval_linkk function does?
What would be the formula to calculate rmse from the provided residuals.

Thanks,

Best