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rsi.src.js
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rsi.src.js
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var changes = [],
lastClose,
previousAverageGain,
previousAverageLoss;
function getRunUpCount (periods) {
return periods * 2;
}
function getBufferSize (periods) {
return 0;
}
function getStudyAxisConfig () {
return {
tickPositions: [0, 30, 70, 100]
};
}
function validate (periods) {
if (typeof periods !== "number") {
error("RSI periods must be a number");
}
if (periods % 1 !== 0) {
error("RSI periods must be an integer");
}
if (periods > 100) {
error("RSI maximum periods is 100");
}
if (periods <= 0) {
error("RSI periods must be greater than zero");
}
}
function onIntervalClose (periods) {
var currentGain = 0,
currentLoss = 0,
relativeStrength,
relativeStrengthIndex;
if (previousAverageGain === undefined) {
if (!lastClose) {
changes.push(CLOSE - OPEN);
} else {
changes.push(CLOSE - lastClose);
}
lastClose = CLOSE;
if (changes.length < periods) {
return null;
}
if (changes.length > periods) {
changes.shift();
}
previousAverageGain = changes.reduce(function (memo, change) {
if (change > 0) {
return memo + change;
} else {
return 0;
}
}, 0) / periods;
previousAverageLoss = changes.reduce(function (memo, change) {
if (change < 0) {
return memo + Math.abs(change);
} else {
return 0;
}
}, 0) / periods;
} else {
if (CLOSE > lastClose) {
currentGain = CLOSE - lastClose;
} else {
currentLoss = lastClose - CLOSE;
}
lastClose = CLOSE;
previousAverageGain = ((previousAverageGain * (periods - 1)) + currentGain) / periods;
previousAverageLoss = ((previousAverageLoss * (periods - 1)) + currentLoss) / periods;
}
if (previousAverageLoss === 0) {
// Avoid divide by zero scenario
relativeStrengthIndex = 100;
} else {
relativeStrength = previousAverageGain / previousAverageLoss;
relativeStrengthIndex = 100 - (100 / (1 + relativeStrength));
}
return {
overlay: false,
value: relativeStrengthIndex,
precision: 1
};
}