I keep having mistakes

I have just done:

TF1 *func = new TF1(“fit”,fitf,0.0,2500.0,3);

```
func->SetParameters(0,1);
func->SetParNames("constant","coefficient");
func->Draw();
for (int i=0; i<Events; i++)
{
gr.Fit(func);
gr.DrawClone("SAME");
}
And the error is:
```

/Users/root_install/include/TF1.h:726:104: error: type ‘double (double *, double *, double *)’ cannot be used prior to ‘::’*

because it has no members

…ROOT::Internal::GetFunctorType<decltype(ROOT::Internal::GetTheRightOp(&F…

^

/Users/root_install/include/TF1.h:370:41: note: in instantiation of member function 'ROOT::Internal::TF1Builder<double

()(double *, double *, double *)>::Build’ requested here*

ROOT::Internal::TF1Builder::Build(this, f);

^

/Users/root_install/macros/signal.C:62:21: note: in instantiation of function template specialization 'TF1::TF1<double ()(double

*, double *, double *)>’ requested here*

TF1 *func = new TF1(“fit”,fitf,0.0,2500.0,3);*

^

In module ‘MathCore’:

/Users/root_install/include/Math/ParamFunctor.h:125:39: error: too few arguments to function call, expected 3, have 2

return (*f)((T*)x, (double)p);

~~~~ ^

/Users/root_install/include/Math/ParamFunctor.h:95:45: note: in instantiation of member function

'ROOT::Math::ParamFunctorHandler<ROOT::Math::ParamFunctorTempl,

double ()(double *, double *, double *)>::FuncEvaluator<double (*)(double

*, double *, double *), int>::EvalConst’ requested here*

return FuncEvaluator<Func, EvalType>::EvalConst(fFunc,x,p);

^

/Users/root_install/include/Math/ParamFunctor.h:73:4: note: in instantiation of member function

'ROOT::Math::ParamFunctorHandler<ROOT::Math::ParamFunctorTempl,

double ()(double *, double *, double *)>::operator()’ requested here*

ParamFunctorHandler(const Func & fun) : fFunc(fun) {}

^

/Users/root_install/include/Math/ParamFunctor.h:304:17: note: in instantiation of member function

'ROOT::Math::ParamFunctorHandler<ROOT::Math::ParamFunctorTempl,

double ()(double *, double *, double *)>::ParamFunctorHandler’ requested*

here

fImpl(new ParamFunctorHandler<ParamFunctorTempl,Func>(f) )

^

/Users/root_install/include/TF1.h:728:66: note: in instantiation of function template specialization

'ROOT::Math::ParamFunctorTempl::ParamFunctorTempl<double ()(double

*, double *, double *)>’ requested here*

f->fFunctor.reset(new TF1::TF1FunctorPointerImpl<Fnc_t>(ROOT::M…

^

/Users/root_install/include/TF1.h:370:41: note: in instantiation of member function 'ROOT::Internal::TF1Builder<double

()(double *, double *, double *)>::Build’ requested here*

ROOT::Internal::TF1Builder::Build(this, f);

^

/Users/root_install/macros/signal.C:62:21: note: in instantiation of function template specialization 'TF1::TF1<double ()(double

*, double *, double *)>’ requested here

TF1 *func = new TF1(“fit”,fitf,0.0,2500.0,3);*

^

In module ‘MathCore’:

/Users/root_install/include/Math/ParamFunctor.h:121:26: error: too few arguments to function call, expected 3, have 2

return (*f)(x, p);

~~~~ ^

/Users/root_install/include/Math/ParamFunctor.h:91:45: note: in instantiation of member function

'ROOT::Math::ParamFunctorHandler<ROOT::Math::ParamFunctorTempl,

double ()(double *, double *, double *)>::FuncEvaluator<double (*)(double

*, double *, double *), int>::Eval’ requested here*

return FuncEvaluator<Func, EvalType>::Eval(fFunc,x,p);

^

/Users/root_install/include/Math/ParamFunctor.h:73:4: note: in instantiation of member function

'ROOT::Math::ParamFunctorHandler<ROOT::Math::ParamFunctorTempl,

double ()(double *, double *, double *)>::operator()’ requested here*

ParamFunctorHandler(const Func & fun) : fFunc(fun) {}

^

/Users/root_install/include/Math/ParamFunctor.h:304:17: note: in instantiation of member function

'ROOT::Math::ParamFunctorHandler<ROOT::Math::ParamFunctorTempl,

double ()(double *, double *, double *)>::ParamFunctorHandler’ requested*

here

fImpl(new ParamFunctorHandler<ParamFunctorTempl,Func>(f) )

^

/Users/root_install/include/TF1.h:728:66: note: in instantiation of function template specialization

'ROOT::Math::ParamFunctorTempl::ParamFunctorTempl<double ()(double

*, double *, double *)>’ requested here*

f->fFunctor.reset(new TF1::TF1FunctorPointerImpl<Fnc_t>(ROOT::M…

^

/Users/root_install/include/TF1.h:370:41: note: in instantiation of member function 'ROOT::Internal::TF1Builder<double

()(double *, double *, double *)>::Build’ requested here*

ROOT::Internal::TF1Builder::Build(this, f);

^

/Users/root_install/macros/signal.C:62:21: note: in instantiation of function template specialization 'TF1::TF1<double ()(double

*, double *, double *)>’ requested here

TF1 *func = new TF1(“fit”,fitf,0.0,2500.0,3);