Setting decimal in TLatex

Hi guys, I’m creating an animation and I got many decimals in one parameter I’m chaing, and I’d like to show just one decimal, but no idea how to set due to it is not in the axis. Let me present the animation to be more clear (see the attachment).

And here the important part of the code:

  int steps=100, k;
  double a = 0.27, b = 0.12; double c;
  TH1D * h2 = R.GuardarEnTH1(argv[1],"Simulation");
  TString  formula;
  TLatex latex;
  latex.SetTextSize(0.04);
  latex.SetTextAlign(13);  
  for(k, c=0.1 ; k<=steps; c+=0.1 , k++ )
    {
      formula = "0.27*E+0.12#sqrt{E}+";
      formula+=c;
      TH1D *h2f= p.AgregarFWHM(h2, "", a,b,c);
      latex.DrawLatex(1000, 5000 , formula);
}
      h2f->Draw();
      R.DibujarAjuste(400, 4000 ,formula);
      
      c1->Print("animation.gif+30");
      formula.Clear();
    }


formula = Form("0.27*E+0.12#sqrt{E}+%3.1g",c);