#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
using namespace std;

class TakeCos{
public:
  void operator()(double& x){ x=cos(x); } // function object  
};
void doubleout(double& x) { cout<< x<<" ";}
void vector_out(vector<double> & x){
  for_each (x.begin(), x.end(), doubleout);
  cout<<endl;
}
int main () {
  vector<double> x;
  x.push_back(1.1); x.push_back(2.2);  x.push_back(3.3);
  cout << "vector x      : ";
  vector_out(x);
  TakeCos Cos ; // create one instance of TakeCos, same time one function object
  for_each(x.begin(), x.end(), Cos); 
  cout << "vector cos(x) : ";
  vector_out(x);
  return 0;
}