TD DeMarker

Tom DeMark's oscillator. Compares rolling sums of "DeMax" (high above previous high) against "DeMin" (low below previous low) to produce a 0-1 bounded momentum oscillator. Conceptually similar to RSI but built from extreme-bar comparisons rather than close-to-close differences — diverges from RSI in high-wick markets where RSI ignores the wicks but DeMark captures them.

Quick reference

Item	Value
Family	DeMark
Input type	Candle (uses high, low)
Output type	f64
Output range	[0, 1]
Default parameters	period = 14
Warmup period	period + 1
Interpretation	Above 0.7 overbought; below 0.3 oversold

Formula

demax_t = max(high_t - high_{t-1}, 0)
demin_t = max(low_{t-1} - low_t, 0)

DeMarker_t = sum(demax over period) /
             (sum(demax over period) + sum(demin over period))

A 0-1 bounded oscillator: 1 = pure new-high streak; 0 = pure new-low streak; 0.5 = balanced. See crates/wickra-core/src/indicators/td_demarker.rs.

Parameters

Name	Type	Default	Constraint	Description
period	usize	14	> 0	Rolling-sum window.

TdDeMarker::new returns Error::PeriodZero for period == 0. TdDeMarker::classic() returns the 14 factory.

Inputs / Outputs

Indicator<Input = Candle, Output = f64>. Python: TdDeMarker(period).batch(high, low) returns a 1-D np.ndarray with NaN in the warmup prefix. Node: same shape; update(candle) returns number | null.

Warmup

warmup_period() == period + 1. The first demax / demin calculation needs a previous bar; the rolling sum then needs period of those.

Edge cases

• Both DeMax and DeMin sums zero. Indicator returns 0.5 by convention (matches DeMark's published rule for the all-flat case).
• Constant series. demax = demin = 0 every bar → indicator = 0.5.
• Reset. Clears the high/low buffer and both rolling sums.
• NaN / infinity. Rejected by Candle::new upstream.

Examples

Rust

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

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let candles: Vec<Candle> = (0..30).map(|i| {
        let b = 100.0 + f64::from(i);
        Candle::new(b, b + 1.0, b - 1.0, b, 1.0, i as i64).unwrap()
    }).collect();
    let mut td = TdDeMarker::new(14)?;
    println!("row 20 = {:?}", td.batch(&candles)[20]);
    Ok(())
}

Python

import numpy as np
import wickra as ta

base = 100 + np.arange(30, dtype=float)
td = ta.TdDeMarker(14)
out = td.batch(base + 1, base - 1)
print('row 20:', out[20])

Node

const wickra = require('wickra');
const td = new wickra.TdDeMarker(14);
const base = Array.from({ length: 30 }, (_, i) => 100 + i);
console.log('row 20:', td.batch(base.map(b => b + 1), base.map(b => b - 1))[20]);

Streaming

use wickra::{Candle, Indicator, TdDeMarker};

let mut td = TdDeMarker::new(14).unwrap();
let candle_stream: Vec<wickra::Candle> = Vec::new(); // your live OHLCV candle feed
for bar in candle_stream {
    if let Some(v) = td.update(bar) {
        if v > 0.7 { /* overbought */ }
        if v < 0.3 { /* oversold */ }
    }
}

Interpretation

• DeMarker > 0.7. Recent action dominated by new highs — overbought, look for distribution.
• DeMarker < 0.3. Recent action dominated by new lows — oversold, look for accumulation.
• Crossings of 0.5. Trend-strength changes; less actionable than the extremes.
• Vs RSI. Both 0-1 oscillators but DeMarker is built on high/low extensions (extreme-bar comparisons), RSI on close-to-close differences. DeMarker diverges from RSI in high-wick markets (e.g. crypto on news bars) where wicks carry important information that RSI's close-based view misses.

Common pitfalls

• Confusing DeMarker with RSI thresholds. Different scales (0..1 vs 0..100) and different distributional properties. Don't translate RSI < 30 literally into DeMarker < 0.3.
• Treating crossings of 0.5 as signals. They're informational drifts; canonical signals are the 0.7 / 0.3 extremes.
• Too-short period. period = 5 gives a hyper-active oscillator that whips on every bar. DeMark's published default 14 is the recommended starting point.

References

• Tom DeMark, The New Science of Technical Analysis (1994), ch. 4 — DeMarker derivation.

See also

• Rsi — close-based momentum oscillator.
• TdRei — DeMark's narrower 5-bar oscillator.
• TdSequential — paired Setup + Countdown system.
• Indicators-Overview — full taxonomy.