Passing a multidimensional vector (matrix) to a Function in C++

In am having problems passing a multidimensonal array to a function from the main. Here is an example of the problem:

  double function(int**);
  int main(){
     vector< vector<int> > my_vec;
     double result;
     result = funtion(my_vec); //it doesnt recognize the type. my vec
     return 0;
     }
    double function(int**my_vec){
         // DOES STUFF WITH THE 
         }

What is the correct way of passing the matrix to the function ??

Many Thanks,

Duccio