Simultaneous Graph Fitting

ROOT
1

Hi there,

I am trying to fit to two separate graphs, with two separate functions that have common parameters.

I have two data sets in (x,y), one for each graph. The two functions may be expressed, giving common parameters the same parameter number:

Graph 1 - y = [3] + sqrt([0]+[1]x[3]+[2]xx*[3][3])/x
Graph 2 - y = [4] + sqrt([0]+[1]x[4]+[2]xx[4]*[4])/x

I wish to fit simultaneously to constrain the common parameters [0], [1], [2], and I cannot see how to simply combine the data sets for a single fit. I have tried to adapt $ROOTSYS/tutorials/fit/combinedFit.C for use with graphs instead of histograms, but have so far failed to get sensible numbers. If anyone could help me with this, I would be much obliged!

Andy

2

Hi,

You should be able to adapt the tutorial combinedFit.C and use it with Graphs. Which problem did you have in doing this ?

Lorenzo