All Fixed Parameters INFO from Fitting Not Suppressable

Hello! I’ve run into an issue using the basic TH1::Fit() with a TF1 that has all fixed parameters. My idea is to try a Gaussian with known amplitude/sigma at various mean values in a TH1, extract the chi2, and store them away for histogramming later. In principle this is easy to do:

root [1] TF1 *fGauss = new TF1(“fGauss”, “gaus”)
root [2] TH1D *hTest = new TH1D(“Test”, “Test Hist”, 10, 0.0, 1.0)
root [3] hTest->FillRandom(“gaus”, 5000)

Fitting this histogram yields the expected result, but since I’m doing many fits at different means (~10000 times per event), I don’t want it to draw or output fit information, so I call Fit() quietly:

root [4] hTest->Fit(“fGauss”, “Q”)

and this fits as expected. However, the whole point is fitting with entirely fixed parameters so that I may easily extract the chi2. However using “B” to fix the parameters,

root [5] hTest->Fit(“fGauss”, “BQ”)
Info in TMinuitMinimizer::Minimize: There are no free parameter - just compute the function value

I can’t find a way to suppress this…warning? without changing the ROOT source. I understand that in this case, it is simply computing the TF1 value at the point, which I can do on my own, however that won’t give me the chi2 (easily at least). Am I approaching this in the wrong way, or should Q be suppressing these messages?


I will fix this now in the trunk and 5.34 patches to suppress the message when you have selected the “Q” option.
However, you can also suppress it now yourself by doing:


which will ignore all Info messages produced by ROOT.

Thank you for reporting this issue
Best Regards