/**
* Keltner Channels Indicator
* Volatility-based channels using ATR around EMA
*/
import { calculateEMA } from './moving-averages';
import { calculateATR } from './volatility';
export function calculateKeltnerChannels(highs, lows, closes, emaPeriod = 20, atrPeriod = 14, multiplier = 2) {
if (closes.length < Math.max(emaPeriod, atrPeriod + 1)) {
return {
middle: null,
upper: null,
lower: null,
bandwidth: null,
position: null,
trend: null,
};
}
// Calculate EMA for middle line
const ema = calculateEMA(closes, emaPeriod);
const currentEMA = ema[ema.length - 1];
if (!currentEMA) {
return {
middle: null,
upper: null,
lower: null,
bandwidth: null,
position: null,
trend: null,
};
}
// Calculate ATR
const atr = calculateATR(highs, lows, closes, atrPeriod);
const currentATR = atr[atr.length - 1];
if (!currentATR) {
return {
middle: currentEMA,
upper: null,
lower: null,
bandwidth: null,
position: null,
trend: null,
};
}
// Calculate channels
const upper = currentEMA + (multiplier * currentATR);
const lower = currentEMA - (multiplier * currentATR);
const bandwidth = (upper - lower) / currentEMA;
// Determine trend (expanding/contracting based on ATR change)
let trend = null;
if (atr.length >= 2) {
const currentATR = atr[atr.length - 1];
const previousATR = atr[atr.length - 2];
const atrChange = (currentATR - previousATR) / previousATR;
if (atrChange > 0.05)
trend = 'expanding'; // ATR increased > 5%
else if (atrChange < -0.05)
trend = 'contracting'; // ATR decreased > 5%
else
trend = 'stable';
}
return {
middle: currentEMA,
upper,
lower,
bandwidth,
position: null, // Will be set by caller with current price
trend,
};
}
