wickra/docs/wiki/indicators/momentum/Indicator-AcceleratorOscillator.md

AcceleratorOscillator

Accelerator Oscillator (AC) — Bill Williams' measure of how fast momentum itself is changing.

Quick reference

Field	Value
Family	Price Oscillators
Input type	Candle (uses high, low)
Output type	f64
Output range	unbounded around zero
Default parameters	ao_fast = 5, ao_slow = 34, signal_period = 5 (Python)
Warmup period	ao_slow + signal_period − 1
Interpretation	Acceleration of momentum; zero-line crossings lead the Awesome Oscillator.

Formula

AO = SMA(median, ao_fast) − SMA(median, ao_slow)   (the Awesome Oscillator)
AC = AO − SMA(AO, signal_period)

Where the AwesomeOscillator measures momentum, the Accelerator measures the change in momentum — it is the AO minus a short moving average of itself. Because acceleration leads speed, the AC tends to turn before the AO does. Bill Williams' classic configuration is the (5, 34) AO with a 5-period signal average.

Parameters

• ao_fast, ao_slow — the underlying Awesome Oscillator periods (5, 34).
• signal_period — the moving average of the AO subtracted from it (5).

AcceleratorOscillator::classic() returns the (5, 34, 5) configuration.

Inputs / Outputs

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

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

It is a candle-input indicator — the inner Awesome Oscillator reads the median price (high + low) / 2. Python's streaming update accepts a 6-tuple or a dict; the batch helper takes high, low numpy arrays. Node and WASM expose update(high, low) and the matching batch.

Warmup

AcceleratorOscillator::classic().warmup_period() == 38. The AO first emits at candle ao_slow; the signal average then needs signal_period AO values.

Edge cases

• Flat market. A flat series gives AO = 0, so AC = 0 throughout.
• ao_fast >= ao_slow. Rejected at construction.
• Reset. ac.reset() clears the AO and the signal average.

Examples

Rust

use wickra::{BatchExt, Candle, Indicator, AcceleratorOscillator};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut ac = AcceleratorOscillator::classic();
    let candles: Vec<Candle> = (0..60)
        .map(|i| Candle::new(10.0, 11.0, 9.0, 10.0, 1.0, i).unwrap())
        .collect();
    println!("{:?}", ac.batch(&candles).last().unwrap());
    Ok(())
}

Output:

Some(0.0)

A flat market produces a flat AO and therefore a zero Accelerator.

Python

import numpy as np
import wickra as ta

ac = ta.AcceleratorOscillator(5, 34, 5)
n = 60
print(ac.batch(np.full(n, 11.0), np.full(n, 9.0))[-1])

Output:

0.0

Node

const ta = require('wickra');
const ac = new ta.AcceleratorOscillator(5, 34, 5);
const out = ac.batch(Array(60).fill(11), Array(60).fill(9));
console.log(out[out.length - 1]);

Output:

0

Interpretation

Trade the Accelerator like a momentum-acceleration gauge: bars rising above the zero line mean momentum is building, bars falling below mean it is fading. Because it leads the Awesome Oscillator, a colour change in the AC is an early warning that the AO — and price momentum — is about to turn.

Common pitfalls

• Reading the level. Only the sign and the slope matter; the magnitude scales with the instrument.
• Feeding it scalar prices. It needs the high/low bar.

References

Bill Williams' Accelerator Oscillator, from Trading Chaos.

See also

• Indicator-AwesomeOscillator.md — the momentum oscillator the Accelerator is built on.
• Indicators-Overview.md — the full taxonomy.