STOCH

Summary

Slow Stochastic oscillator: locates the close within the high-low range over a lookback period, then double-smooths it. Returns the Slow-%K and Slow-%D lines. SlowK/SlowD > 80 overbought, < 20 oversold; %K crossing %D signals momentum shifts.

Formula

FastK = 100*(Close - LL_n)/(HH_n - LL_n), n = FastK_Period (LL/HH = lowest low / highest high over n)
SlowK = MA(FastK, SlowK_Period, SlowK_MAType)
SlowD = MA(SlowK, SlowD_Period, SlowD_MAType)

Notes

When the high-low range over the window is zero, the raw stochastic is set to 0 instead of being undefined.

Inputs

inHigh — High price of each bar
inLow — Low price of each bar
inClose — Close price of each bar

Outputs

outSlowK — Raw FastK smoothed by SlowK_Period MA
outSlowD — Signal line: SlowK smoothed by SlowD_Period MA

Parameters

Parameter	Type	Default	Accepted values	Description
`optInFastK_Period`	integer	5	1–100000	Lookback window for the raw %K high-low range
`optInSlowK_Period`	integer	3	1–100000	Smoothing period turning FastK into SlowK
`optInSlowK_MAType`	MAType	SMA (0)	any MAType	MA type used to smooth into SlowK
`optInSlowD_Period`	integer	3	1–100000	Smoothing period for the SlowD signal line
`optInSlowD_MAType`	MAType	SMA (0)	any MAType	MA type used for the SlowD line

MAType values: 0 SMA · 1 EMA · 2 WMA · 3 DEMA · 4 TEMA · 5 TRIMA · 6 KAMA · 7 MAMA · 8 T3 · 9 HMA · 10 DISABLED

Properties

Numerical Stability: Depends on MA Type — This function's default, SMA, is start-independent.

Display Flags
☐ Overlap Input
✅ Independent Y-Axis i
☐ Candlestick

Implementation

TA-Lib Definition: stoch.c · stoch.yaml

Native	File
C	`ta_STOCH.c`
Rust	`stoch.rs`
Java	`Core_STOCH.java`

TA-Lib is also available for Python, R and more using a wrapper.

Aliases

Stochastic, Stochastic Oscillator, Slow Stochastic