Rocp

Rate of Change Percentage (ROCP) — (close − close[period]) / close[period], the same momentum measure as Roc expressed as a raw fraction.

Quick reference

Field	Value
Family	Momentum Oscillators
Input type	f64 (single close)
Output type	f64
Output range	unbounded; 0 = no change, > 0 advance, < 0 decline
Default parameters	period is required
Warmup period	period + 1
Interpretation	Fractional momentum: 0.05 means price is 5% above where it was period bars ago.

Formula

For t >= period (after warmup):

ROCP = (close_t − close_{t-period}) / close_{t-period}

This is exactly Roc divided by 100 — Roc = 100 · ROCP. The fractional form is convenient when you want to compound or combine momentum with other fractional quantities (e.g. returns) without rescaling. Where the reference price close_{t-period} is zero the result is guarded to 0. See crates/wickra-core/src/indicators/rocp.rs.

Parameters

Name	Type	Default	Valid range	Description	Source
period	usize	none	>= 1	Lookback distance in bars. period = 0 errors with Error::PeriodZero.	rocp.rs:40

Inputs / Outputs

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

use wickra::{Indicator, Rocp};
// Rocp: Input = f64, Output = f64
const _: fn(&mut Rocp, f64) -> Option<f64> = <Rocp as Indicator>::update;

Python streams as float | None, batches as a 1-D numpy.ndarray (NaN for warmup). Node streams as number | null, batches as Array<number> with NaN placeholders.

Warmup

Rocp::new(period).warmup_period() == period + 1 (the accessors_report_config test pins warmup_period() == 4 for period = 3). The first value is emitted at input index period — the (period + 1)-th input — once a reference price period bars back is available. The known_value_is_a_fraction test pins out[0] == None.

Edge cases

• Zero reference price. When close[period] == 0 the division is guarded and the output is 0 rather than infinity/NaN. The unit test zero_reference_price_reports_zero pins this ([0, 5], period 1 → 0).
• Constant series. A flat price returns 0 for every emitted value. The unit test constant_series_yields_zero pins this.
• Non-finite input. NaN / infinity inputs are ignored: they leave the window untouched and the last computed value is returned, matching the SMA / EMA convention. The unit test non_finite_input_holds_last pins this.
• Reset. r.reset() clears the window and last value. The unit test reset_clears_state pins this.

Examples

Rust

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

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut r = Rocp::new(1)?;
    let out: Vec<Option<f64>> = r.batch(&[10.0, 11.0]);
    println!("{:?}", out);
    Ok(())
}

Output:

[None, Some(0.1)]

Period 1 over [10, 11]: (11 − 10) / 10 = 0.1. This matches the known_value_is_a_fraction unit test in crates/wickra-core/src/indicators/rocp.rs.

Python

import numpy as np
import wickra as ta

r = ta.Rocp(1)
print(r.batch(np.array([10.0, 11.0])))

Output:

[ nan 0.1]

Node

const ta = require('wickra');
const r = new ta.Rocp(1);
for (const x of [10, 11]) console.log(x, '->', r.update(x));

Output:

10 -> null
11 -> 0.1

Interpretation

Rocp is plain momentum on a fractional scale. Read it as a percentage change: 0.1 is +10% versus period bars ago, -0.1 is −10%. Zero crossings mark where price returns to its level period bars back; the magnitude is the strength of the move. Because it is unbounded it is best used for divergence, threshold breaks, or as a feature fed into downstream models rather than as an overbought/oversold gauge.

Choose Rocp over Roc when you want a fraction (0.05) rather than a percentage (5.0); choose Rocr / Rocr100 when you want the ratio form centred on 1 / 100.

Common pitfalls

• Scale confusion with Roc. Rocp is Roc / 100. A 5% move reads 0.05 here and 5.0 from Roc; do not compare thresholds across the two without rescaling.
• Reference-price zero. A guarded 0 (not an error or NaN) is returned when the lookback price is exactly zero — relevant for spreads or de-meaned series that can cross zero.

References

The Rate of Change Percentage is TA-Lib's ROCP function; it is the fractional form of the classic Rate of Change momentum oscillator.

See also

• Indicator-Roc — the percentage form (100 · ROCP).
• Indicator-Rocr — the ratio form (close / close[period]).
• Indicator-Rocr100 — the ratio form ×100.
• Indicators-Overview — the full taxonomy.