Implementation of exponentiation by squaring in C#. See http://en.wikipedia.org/wiki/Exponentiation_by_squaring

PowerBySquaring.cs

public static int PowerBySquaring(int baseNumber, int exponent)
{
    int result = 1;
    while (exponent != 0)
    {
        if ((exponent & 1)==1)
        {
            result *= baseNumber;
        }
        exponent >>= 1;
        baseNumber *= baseNumber;
    }

    return result;
}

public static double PowerBySquaring(double baseNumber, int exponent)
{
    double result = 1.0;
    while (exponent > 0)
    {
        if (exponent % 2 == 1)
            result *= baseNumber;
        exponent >>= 1;
        baseNumber *= baseNumber;
    }

    return result;
}