// functions for properties of sphere
#include <iostream>
#include <math.h>
using namespace std;
const double pi = 3.1416;

// function declarations
double mass(double r, double rho);
double volume(double r);

// function implementations

double mass(double r, double rho) 
{
  return rho * volume(r);
}

double volume(double r) 
{
  const double pi = 3.1416;
  return 4./3. * pi * pow(r, 3.);
}