getting a fitted function

Hi,
I wrote a macro which does a polynom fit g1=new TF1("m1","pol2", 5.71,5.75);

   TH1F *h1 =new TH1F("g1","",250,5.6,6); .....

    h1->Draw();
    h1->Fit(g1,"R");
which works alright. my question is how can I get the result of the fit. I need to find the derivate of the result.

Many Thanks,
Nasim

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