less.js/lib/less/functions/math.js

var functionRegistry = require("./function-registry"),
    mathHelper = require("./math-helper.js");

var mathFunctions = {
    // name,  unit
    ceil:  null,
    floor: null,
    sqrt:  null,
    abs:   null,
    tan:   "",
    sin:   "",
    cos:   "",
    atan:  "rad",
    asin:  "rad",
    acos:  "rad"
};

for (var f in mathFunctions) {
    if (mathFunctions.hasOwnProperty(f)) {
        mathFunctions[f] = mathHelper._math.bind(null, Math[f], mathFunctions[f]);
    }
}

mathFunctions.round = function (n, f) {
    var fraction = typeof f === "undefined" ? 0 : f.value;
    return mathHelper._math(function(num) { return num.toFixed(fraction); }, null, n);
};

functionRegistry.addMultiple(mathFunctions);