07-19-2014 03:37 AM
I am using "nonliear curve fit.vi" with defined Chebychev Polynomial function to fit XY data. Strangely, if I enlarge the upturn part, I clearly see the fitting results show multi-lines (2-4) . Please the the attached snapshot.
weitong
LV2013
07-19-2014 03:50 AM
Can you please attach the actual VI?
07-19-2014 08:36 AM
Thanks.
I found the reason: the data X values are not mononicaly, i. e. there are local oscillations at some region.
After sorting the raw data, the fitting results show single line.
Is the sorting of X values necessary before Chebychev Polynomial fitting?