mathjs/lib/function/statistics/min.js

'use strict';

module.exports = function (math) {
  var Matrix = math.type.Matrix,
      collection = math.collection,

      isCollection = collection.isCollection;

  /**
   * Compute the maximum value of a matrix or a  list of values.
   * In case of a multi dimensional array, the maximum of the flattened array
   * will be calculated. When `dim` is provided, the maximum over the selected
   * dimension will be calculated. Parameter `dim` is zero-based.
   *
   * Syntax:
   *
   *     math.min(a, b, c, ...)
   *     math.min(A)
   *     math.min(A, dim)
   *
   * Examples:
   *
   *     math.min(2, 1, 4, 3);                  // returns 1
   *     math.min([2, 1, 4, 3]);                // returns 1
   *
   *     // maximum over a specified dimension (zero-based)
   *     math.min([[2, 5], [4, 3], [1, 7]], 0); // returns [1, 3]
   *     math.min([[2, 5], [4, 3], [1, 7]], 1); // returns [2, 3, 1]
   *
   *     math.max(2.7, 7.1, -4.5, 2.0, 4.1);    // returns 7.1
   *     math.min(2.7, 7.1, -4.5, 2.0, 4.1);    // returns -4.5
   *
   * See also:
   *
   *    mean, median, max, prod, std, sum, var
   *
   * @param {... *} args  A single matrix or or multiple scalar values
   * @return {*} The minimum value
   */
  math.min = function min(args) {
    if (arguments.length == 0) {
      throw new SyntaxError('Function min requires one or more parameters (0 provided)');
    }

    if (isCollection(args)) {
      if (arguments.length == 1) {
        // min([a, b, c, d, ...])
        return _min(args);
      }
      else if (arguments.length == 2) {
        // min([a, b, c, d, ...], dim)
        return collection.reduce(arguments[0], arguments[1], _getSmaller);
      }
      else {
        throw new SyntaxError('Wrong number of parameters');
      }
    }
    else {
      // min(a, b, c, d, ...)
      return _min(arguments);
    }
  };

  function _getSmaller(x, y){
	  return math.smaller(x, y)  ? x : y;
  }

  /**
   * Recursively calculate the minimum value in an n-dimensional array
   * @param {Array} array
   * @return {Number} min
   * @private
   */
  function _min(array) {
    var min = undefined;

    collection.deepForEach(array, function (value) {
      if (min === undefined || math.smaller(value, min)) {
        min = value;
      }
    });

    if (min === undefined) {
      throw new Error('Cannot calculate min of an empty array');
    }

    return min;
  }
};