STOCHF

Summary

Fast Stochastic Oscillator: the raw %K line and its moving-average-smoothed %D line. Unlike STOCH (which slows both lines), STOCHF returns the unsmoothed FastK and FastD. Oscillates 0-100; >80 overbought, <20 oversold.

Formula

FastK = 100 * (Close - LowestLow) / (HighestHigh - LowestLow), over the last FastK_Period bars (incl. today)
FastD = MA(FastK, FastD_Period, FastD_MAType)

Notes

When the high-low range over the window is zero, %K 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

outFastK — Raw %K stochastic line
outFastD — MA-smoothed %K (signal line)

Parameters

Parameter	Type	Default	Accepted values	Description
`optInFastK_Period`	integer	5	1–100000	Lookback window for the highest-high/lowest-low of Fast-K
`optInFastD_Period`	integer	3	1–100000	Smoothing period for the Fast-D line
`optInFastD_MAType`	MAType	SMA (0)	any MAType	Moving-average type used to smooth Fast-D

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: stochf.c · stochf.yaml

Native	File
C	`ta_STOCHF.c`
Rust	`stochf.rs`
Java	`Core_STOCHF.java`

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

Aliases

Stochastic Fast, Fast Stochastic Oscillator