math-standard-deviation/index.js

Small javascript / nodejs module to calculate the standard deviation

function mean (dataset) {
    var sum = dataset.reduce((a, b) => a + b, 0);
    var m = sum / dataset.length;
    return m;
}

function deviation (dataset, unbiased) {

    var m = mean(dataset)

    var total = 0;
    dataset.forEach(val => {
        total+= Math.pow(val - m, 2);
    });

    var n = dataset.length;
    if (unbiased) {
        n--;
    } 

    return Math.sqrt(total / n);
}

function standardDeviation (dataset) {
    return deviation(dataset, true);
}

function populationStandardDeviation(dataset) {
    return deviation(dataset)
}

module.exports = {
    populationStandardDeviation: populationStandardDeviation,
    standardDeviation: standardDeviation,
    mean: mean
}