/**
* Alligator Indicator (Bill Williams)
* Three smoothed moving averages representing different phases of market
*/
import { calculateSMMA } from './smma';
export function calculateAlligator(closes, jawPeriod = 13, teethPeriod = 8, lipsPeriod = 5, jawShift = 8, teethShift = 5, lipsShift = 3) {
if (closes.length < jawPeriod + jawShift) {
return {
jaw: null,
teeth: null,
lips: null,
phase: null,
trend: null,
};
}
// Calculate SMMA for each line
const jawSMMA = calculateSMMA(closes, jawPeriod);
const teethSMMA = calculateSMMA(closes, teethPeriod);
const lipsSMMA = calculateSMMA(closes, lipsPeriod);
// Apply shifts (looking backwards from current position)
const currentIndex = closes.length - 1;
const jawIndex = currentIndex - jawShift;
const teethIndex = currentIndex - teethShift;
const lipsIndex = currentIndex - lipsShift;
const jaw = jawIndex >= 0 && jawIndex < jawSMMA.length ? jawSMMA[jawIndex] : null;
const teeth = teethIndex >= 0 && teethIndex < teethSMMA.length ? teethSMMA[teethIndex] : null;
const lips = lipsIndex >= 0 && lipsIndex < lipsSMMA.length ? lipsSMMA[lipsIndex] : null;
// Determine market phase based on Alligator lines
let phase = null;
let trend = null;
if (jaw !== null && teeth !== null && lips !== null) {
// Check if lines are intertwined (sleeping phase)
const linesClose = Math.abs(jaw - teeth) < 0.001 && Math.abs(teeth - lips) < 0.001 && Math.abs(jaw - lips) < 0.001;
if (linesClose) {
phase = 'sleeping';
trend = 'neutral';
}
else {
// Check order of lines
if (lips > teeth && teeth > jaw) {
phase = 'eating';
trend = 'bullish';
}
else if (jaw > teeth && teeth > lips) {
phase = 'satiated';
trend = 'bearish';
}
else {
phase = 'waking';
trend = 'neutral';
}
}
}
return {
jaw,
teeth,
lips,
phase,
trend,
};
}
