mathjs/src/function/statistics/max.js

/**
 * Compute the maximum value of a list of values, max(a, b, c, ...)
 * @param {... *} args  one or multiple arguments
 * @return {*} res
 */
function max(args) {
    if (arguments.length == 0) {
        throw new Error('Function max requires one or more parameters (0 provided)');
    }

    if (args instanceof Array || args instanceof Matrix || args instanceof Range) {
        // max([a, b, c, d, ...]])
        if (arguments.length > 1) {
            throw Error('Wrong number of parameters (1 matrix or multiple scalars expected)');
        }

        var size = math.size(args);

        if (size.length == 1) {
            // vector
            if (args.length == 0) {
                throw new Error('Cannot calculate max of an empty vector');
            }

            return _max(args.valueOf());
        }
        else if (size.length == 2) {
            // 2 dimensional matrix
            if (size[0] == 0 || size[1] == 0) {
                throw new Error('Cannot calculate max of an empty matrix');
            }
            if (args instanceof Array) {
                return _max2(args, size[0], size[1]);
            }
            else if (args instanceof Matrix || args instanceof Range) {
                return new Matrix(_max2(args.valueOf(), size[0], size[1]));
            }
            else {
                throw newUnsupportedTypeError('max', args);
            }
        }
        else {
            // TODO: implement max for n-dimensional matrices
            throw new RangeError('Cannot calculate max for multi dimensional matrix');
        }
    }
    else {
        // max(a, b, c, d, ...)
        return _max(arguments);
    }
}

math.max = max;

/**
 * Calculate the max of a one dimensional array
 * @param {Array} array
 * @return {Number} max
 * @private
 */
function _max(array) {
    var larger = math.larger;
    var res = array[0];
    for (var i = 1, iMax = array.length; i < iMax; i++) {
        var value = array[i];
        if (larger(value, res)) {
            res = value;
        }
    }
    return res;
}

/**
 * Calculate the max of a two dimensional array
 * @param {Array} array
 * @param {Number} rows
 * @param {Number} cols
 * @return {Number[]} max
 * @private
 */
function _max2(array, rows, cols) {
    var larger = math.larger;
    var res = [];
    for (var c = 0; c < cols; c++) {
        var max = array[0][c];
        for (var r = 1; r < rows; r++) {
            var value = array[r][c];
            if (larger(value, max)) {
                max = value;
            }
        }
        res[c] = max;
    }
    return res;
}

/**
 * Function documentation
 */
max.doc = {
    'name': 'max',
    'category': 'Statistics',
    'syntax': [
        'max(a, b, c, ...)'
    ],
    'description': 'Compute the maximum value of a list of values.',
    'examples': [
        'max(2, 3, 4, 1)',
        'max(2.7, 7.1, -4.5, 2.0, 4.1)',
        'min(2.7, 7.1, -4.5, 2.0, 4.1)'
    ],
    'seealso': [
        'sum',
        'prod',
        'avg',
        'var',
        'std',
        'min',
        'median'
    ]
};