Fast, Slow and Full Stochastic
The Fast Stochastic indicator was developed by George Lane to show potential future reversals based on momentum.
The Fast Stochastic plots the location of the Close relative to the Highest High - Lowest Low range for the requested Period.
When the indicator crosses below the oversold line (20) this could indicate a Buy signal and when the indicator crosses above the overbought line (80) this could indicate a Sell signal.
Fast Stochastic %K = (Close - Lowest Low for Period) / (Highest High for Period - Lowest Low for Period) * 100
Fast Stochastic %D = 3 day SMA of %K
The default Period for %K is 14 and the default Period for %D is 3.
The Slow Stochastic is a smoothed version of the Fast Stochastic. It takes a 3 day SMA of Fast Stochastic %K as its %K and applies a 3 day SMA to that to get Slow Stochastic %D.
Slow Stochastic %K = Fast Stochastic %D (3 days Periods).
The Full Stochastic is similar to the Slow but has an additional parameter to allow you to specify the SMA period instead of just using 3.