Einstein mass-to-energ

/* This program computes energy from a given mass using Einstein's 

mass-to-energy conversion equation.

Input: the mass (in kilograms) being converted to energy

Output: the amount of energy (in kilojoules) corresponding to mass

---------------------------------------------------------------------------*/

#include <iostream> // cin, cout, <<, >>

#include <cmath> // pow()

using namespace std;

int main()

{

 const double SPEED_OF_LIGHT = 2.997925e8; // meters/sec

 double mass;

 cout << "To find the amount of energy obtained from a given mass,\n"

"enter a mass (in kilograms): ";

 cin >> mass; // get mass

 // compute energy

 double energy = mass * pow(SPEED_OF_LIGHT, 2);

 // display energy

 cout << mass << " kilograms of matter will release\n"

 << energy << " kilojoules of energy.\n";

}