Equation for mining profit I'm a newbie. 

What is the basic equation for computing profit from mining given gigahash per second of the miner, timeframe, miner costs, and current bitcoin economy stats like mining difficulty and dollars per coin?

And what are some URLs that have these stats always up to date?

I'm looking for the equation, not an online calculator.
The average amount of time (in seconds) to find a single share is:

difficulty * 2^32 / hashrate


In that equation, difficulty is the difficulty of a share and hashrate is your hash rate in hashes per second.  A day has 86,400 seconds in it, so the number of shares you'll find in 24 hours is:

86,400 / (difficulty * 2^32 / hashrate)


A slightly more complex formula, using PHP:

$hashTime = ((float) $difficulty) * (pow(2.0, 32) / ($hashRate * 1000.0)) ;
$powerCostPerYear = 365.25 * 24.0 * $powerConsumption / 1000.0 * $electricityRate;
$blocksPerYear =  (365.25 * 24.0 * 3600.0) / $hashTime ;
$coinsPerYear = $blockCoins * $blocksPerYear;
$revenuePerYear = $coinsPerYear * $conversionRate;
$profitPerYear = $revenuePerYear - $powerCostPerYear;
$netProfit1st = $revenuePerYear - $costHardware - $powerCostPerYear;
if ($profitPerYear &lt;= 0) $breakEvenTime = -1;
else $breakEvenTime = $costHardware / ($profitPerYear / (365.25 * 24.0 * 3600.0));