Hi Kevin.
To use combinations of predefined functions, you have to
first create a function that is that combo, and then fit
using that function:
TF1* f1 = new TF1("f1", "gaus(0)+expo(3)");
f1->SetParameters(1, 2, 3, 4, 5); // or some reasonable start values
h1->Fit("f1"); // NB: h1->Fit("gaus(0)+expo(3)") won't work
To the ROOT developers: I know this seems to be a trivial
amount of typing to achieve combo fits, but easy and quick
fitting using different combinations of functions is something
I miss from the old PAW / MinFit days. If syntax like
h1->Fit("gaus(0)+expo(3)+(3*x-1)");
could be added, it would be a nice feature to have. Perhaps
if the string isn't recognized as a function name, you could
attempt to parse it and create a temporary function (similar
to how TTree::Draw() creates a temporary histogram) and fit
using that function.
Happy fitting,
Stephen
On Tue, 27 Jun 2000, Kevin M. Rhodes wrote:
> I'm trying to fit an histogram with a simple addition of two root-defined
> functions, by doing gaus+expo. Is there something special that I need to
> do to get this to work?
>
>
> Kevin Rhodes
> UW Madison
> Amanda Project
>
This archive was generated by hypermail 2b29 : Tue Jan 02 2001 - 11:50:29 MET