If you use functions such as TH1::Fit or TGraph::Fit, you can use
the option "Q" (Quiet) to remove the Minuit print-out.
example
hist->Fit("gaus","Q");
If you use TMinuit directly, you can set the print level
via TMinuit::mnexcm. Example
Double_t arglist[5];
arglist[0] = 0;
Int_t ierr = 0;
gMinuit->mnexcm("SET PRINT",arglist,1,ierr);
For more details, do:
gMinuit->mnhelp("*");
gMinuit->mnhelp("SET");
Rene Brun