Problem with factorial

[alberto.paniate]

I have a very simple problem, I have problems using the factorial. I have included both these libraries:

#include <math.h>
#include “TMath.h”

and I write Factorial(n) but root gives me this error:

error: use of undeclared identifier ‘Factorial’

[couet]

root [1] TMath::Factorial(3)
(double) 6.0000000
root [2] 

[alberto.paniate]

Thank you. If I write that instrunction it worked. But I have to put the Factorial in a program and root gives me me this error:

invalid operands to binary expression ('double' and 'double')
          ris = TMath::Factorial(a) / (TMath::Factorial(j) + TMath::Factorial(a - j))*(prob)^j*(1 - prob)^(a - j) + ris;
``

[Wile_E_Coyote]

Search for “^” in: Wikipedia -> Operators in C and C++

[linev]

a^b is not valid operation, you can use TMath::Power(a,b) instead