Voropaev S.G. wrote: > > Hello, > I have new problem with fitting unsorted data. I am trying to fit unsorted > array X,Y to line. I use object TGraph. Parameters of line is well, but error > is very strange. > Test macro with only 5 data point. (In real life number of data point is > larger, but problem still exist): > > Result of fitting: p0 = 0.64 +- 0.85 !, p1 = -1.04 +- 9.5 !!! > > Where is error? It is my error or not? > > I use ROOT 1.02/00 1 august 1997 ( Valery Fine version) on Windows NT > > With best regards Voropaev S.G. This problem is now fixed in the development version 1.03/02. Result of fitting: p0 = 0.644 +- 0.023, p1 = -1.036 +- 0.256 The fitting algorithm in version 1.02 from TGraph and TGraphErrors objects assumed errors = 1 ! I have now implemented an algorithm that really uses the error specified in TGraphErrors and compute an approximation of the errors for TGraph objects. Thanks for reporting Rene Brun
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