Help with TF2 integral

Newbie
,
4

So, I’ve tried some functions. For instance, first I tried to compute

Int_0^2 dx Int_0^2 dy x*y

using this code:

double func2(const double *x){

	return x[0]*x[1];

}

void integral(){

ROOT::Math::Functor f2(& func2, 2);
double a[2] = {0,2};
double b[2] = {1,2};

ROOT::Math::IntegratorMultiDim ig1(ROOT::Math::IntegrationMultiDim::kADAPTIVE);
ig1.SetFunction(f2);
double val = ig1.Integral(a,b);

cout<<val<<endl;
}

It worked. Them, I tried to change the y integration limits to

Blockquote int_fmin(x)^fmax(x)

like in the code, to simulate the lambda function in the python code:

**Python code**

eLow = lambda u: eMin(u, m_X)
	eHigh = lambda u: eMax(element, m_X,  u)
	integral = integrate.dblquad(integrand, uLow, uHigh, eLow, eHigh)[0]

**cling**

double fmin(x){
	
	return x+1;
	
}

double fmax(x){

	return 2*x+2;

}



void integral(){

ROOT::Math::Functor f2(& func2, 2);
double a[2] = {0,fmin(x[0])};
double b[2] = {1,fmax(x[0])};

ROOT::Math::IntegratorMultiDim ig1(ROOT::Math::IntegrationMultiDim::kADAPTIVE);
ig1.SetFunction(f2);
double val = ig1.Integral(a,b);

cout<<val<<endl;
}

this didn’t worked. If you could provide any help, I would appreciate.

Thank you,
Bests
Ricardo