[tl;dr: read a csv, fit a curve, substract it from the data and write back to the csv]
for a research project I have large amounts of data coming off a profilometer. If you don't know, this is a device that measures the surface profile, in my case of a thin film on a piece of glass, and stores it as X/Y-data in .csv form. Inherent to this data is an error caused by the curvature of the glass plate, that needs to get removed. One such measurement will produce about 40000 lines of data.
I have determined that a quadratic compensation is good enough for what I'm looking to measure, so I have an area in front of and behind the film, as well as in the middle, where there is no film, which can be used to fit a quadratic polynome. The data is quite noisy, so you need to take an average over a couple 100 points. What I would like to do is write a script that reads a CSV file, fits a quadratic polynome to these areas that are known to be the glass plate and subtracts this polynome from the data, so I will hopefully end up with data that is compensated for the curvature of the glass plate, which is then added to the CSV file, ideally in a third column, if that is even possible.
Unfortunately, I am quite new to Matlab, although I managed to cobble together a script that could read a CSV file and plot it in the past, I don't know where to even start with this one. Has anyone ever done this or knows how to do it?