Dimension variable not sent to gsl_monte_vegas_integrate

Roofit and RooStats
1

Hello,

I’m trying to use the GSLMCIntegrator class with root 5.26/00d. I call the Integral function with:

  double result = integrator->Integral(integrand, ndim, xmin, xmax, params);

but when I print the dimension variable from inside my ‘integrand’ function , it’s always zero. Looking at this function:

void GSLMCIntegrator::SetFunction( GSLMonteFuncPointer f,  unsigned int dim, void * p  )
{
   // method to set the a generic integration function
   if(fFunction == 0) fFunction = new  GSLMonteFunctionWrapper();
   fFunction->SetFuncPointer( f );
   fFunction->SetParams ( p );
   fDim = dim;
}

fFunction never gets assigned the dimension variable. If I modify the function to be:

void GSLMCIntegrator::SetFunction( GSLMonteFuncPointer f,  unsigned int dim, void * p  )
{
   // method to set the a generic integration function
   if(fFunction == 0) fFunction = new  GSLMonteFunctionWrapper();
   fFunction->SetFuncPointer( f );
   fFunction->SetParams ( p );
   fFunction->SetDim ( dim ); // <---added this line
   fDim = dim;
}

and recompile root, the dimension is received when my function is called. Is there another way to have the variable passed correctly, or do I have to stick with my recompiled version to have access to the variable? Or perhaps I could just access it using the void* params…

Thanks!

-Aaron