c# map function

var accounts = new Dictionary<string, double>();

// Initialise to zero...

accounts["Fred"] = 0;
accounts["George"] = 0;
accounts["Fred"] = 0;

// Add cash.
accounts["Fred"] += 4.56;
accounts["George"] += 1.00;
accounts["Fred"] += 1.00;

Console.WriteLine("Fred owes me ${0}", accounts["Fred"]);

float Map(float s, float a1, float a2, float b1, float b2)
{
    return b1 + (s - a1) * (b2 - b1) / (a2 - a1);
}