#include "TF3.h"

// class projectiong a TF3(x,y,z)  in a TF2 (x,z)

struct TF3Projector { 
   TF3Projector(TF3 * f, double y) : fFunc(f), fX()  { fX[1] = y;}
   double operator() (const double *x, const double *) { 
      fX[0] = x[0];
      fX[2] = x[1]; 
      return  (*fFunc)( fX );
   }
   TF3 * fFunc; 
   double fX[3];
};

void example_TF23() {

   TF3 * f3 = new TF3("f3","x+y+z");
   TF3Projector * p = new TF3Projector(f3,1);
   TF2 * fxz  = new TF2("f3_xz",p,0,1,0,1,0,"TF3Projector");
   
   fxz->Draw("LEGO"); 

}