wickra/docs/wiki/indicators/price-oscillators/Indicator-Coppock.md

Coppock

Coppock Curve — a long-horizon momentum indicator: a weighted moving average of two rates of change, designed to flag major bottoms.

Quick reference

Field	Value
Family	Price Oscillators
Input type	f64 (single close)
Output type	f64
Output range	unbounded around zero
Default parameters	(roc_long = 14, roc_short = 11, wma_period = 10) (Python)
Warmup period	max(roc_long, roc_short) + wma_period
Interpretation	Long-term momentum; an upturn from below zero is the buy signal.

Formula

Coppock = WMA( ROC(roc_long) + ROC(roc_short), wma_period )

Edwin Coppock built this in 1962 as a long-horizon buy signal for stock indices. The two rates of change blend a slightly longer and a slightly shorter momentum horizon; the Wma smooths their sum. On a monthly chart with the conventional (14, 11, 10) settings, the curve turning up from below zero has historically marked the start of a new bull phase.

Parameters

Name	Type	Default	Valid range	Description
roc_long	usize	14 (Python)	>= 1	Longer ROC period. 0 errors with Error::PeriodZero.
roc_short	usize	11 (Python)	>= 1	Shorter ROC period.
wma_period	usize	10 (Python)	>= 1	WMA smoothing length.

The Python binding defaults the trio to (14, 11, 10). The periods property returns (roc_long, roc_short, wma_period).

Inputs / Outputs

From crates/wickra-core/src/indicators/coppock.rs:

impl Indicator for Coppock {
    type Input = f64;
    type Output = f64;
    // update(&mut self, input: f64) -> Option<f64>
}

A single f64 close in, an Option<f64> out. Python maps this to float | None / numpy.ndarray (NaN warmup); Node to number | null / Array<number> (NaN warmup).

Warmup

warmup_period() == max(roc_long, roc_short) + wma_period. Each ROC emits its first value at input roc_period + 1; the longer ROC is the last to become ready, and the WMA then needs wma_period of the summed ROC values — so the first non-None output lands on input max(roc_long, roc_short) + wma_period.

Edge cases

• Constant series. Both ROCs are 0 on a flat series, so the WMA of zeros — and the curve — is 0 (constant_series_yields_zero pins this).
• NaN / infinity inputs. Non-finite inputs are silently dropped; no component is advanced.
• Reset. coppock.reset() clears both ROCs and the WMA.

Examples

Rust

use wickra::{BatchExt, Indicator, Coppock};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut coppock = Coppock::new(14, 11, 10)?;
    let prices: Vec<f64> = (1..=120).map(|i| 100.0 * 1.01_f64.powi(i)).collect();
    let out = coppock.batch(&prices);
    println!("warmup_period = {}", coppock.warmup_period());
    println!("last > 0: {}", out.last().unwrap().unwrap() > 0.0);
    Ok(())
}

Output:

warmup_period = 24
last > 0: true

A steady uptrend keeps both ROCs positive, so the Coppock Curve stays above zero.

Python

import numpy as np
import wickra as ta

coppock = ta.Coppock()  # (roc_long=14, roc_short=11, wma_period=10)
prices = np.full(60, 100.0)  # flat series
print(coppock.batch(prices)[-1])  # ROCs are 0 -> 0

Output:

0.0

Node

const ta = require('wickra');
const coppock = new ta.Coppock(14, 11, 10);
const prices = Array.from({ length: 120 }, (_, i) => 100 * 1.01 ** i);
console.log('warmupPeriod:', coppock.warmupPeriod());

Interpretation

Coppock is a long-horizon signal, traditionally read on monthly data. The canonical rule is a single one: when the curve has been below zero and turns up, that is a long-term buy. It was not designed to give sell signals — Coppock left exits to other tools. On faster timeframes it behaves as a smoothed momentum oscillator, but its statistical edge is specifically the monthly bottom call.

Common pitfalls

• Using it for sell signals. The Coppock Curve is a buy-only indicator by design; pair it with a separate exit rule.
• Applying it intraday and expecting the historical edge. The documented behaviour is for monthly index charts.

References

E. S. Coppock, "Practical Relative Strength Charting", Barron's (1962). The WMA(ROC(14) + ROC(11), 10) construction here is Coppock's original.

See also

• Indicator-Roc.md — the rate-of-change building block.
• Indicator-Wma.md — the smoothing average.
• Indicators-Overview.md — the full taxonomy.