mathjs/lib/function/arithmetic/unaryMinus.js

'use strict';

module.exports = function (config) {
  var typed = require('typed-function');
  var Complex = require('../../type/Complex');
  var collection = require('../../type/collection');

  /**
   * Inverse the sign of a value, apply a unary minus operation.
   *
   * For matrices, the function is evaluated element wise. Boolean values and
   * strings will be converted to a number. For complex numbers, both real and
   * complex value are inverted.
   *
   * Syntax:
   *
   *    math.unaryMinus(x)
   *
   * Examples:
   *
   *    math.unaryMinus(3.5);      // returns -3.5
   *    math.unaryMinus(-4.2);     // returns 4.2
   *
   * See also:
   *
   *    add, subtract, unaryPlus
   *
   * @param  {Number | BigNumber | Boolean | Complex | Unit | Array | Matrix | null} x Number to be inverted.
   * @return {Number | BigNumber | Complex | Unit | Array | Matrix} Returns the value with inverted sign.
   */
  var unaryMinus = typed('unaryMinus', {
    'number': function (x) {
      return -x;
    },

    'Complex': function (x) {
      return new Complex(
          -x.re,
          -x.im
      );
    },

    'BigNumber': function (x) {
      return x.neg();
    },

    'Unit': function (x) {
      var res = x.clone();
      res.value = -x.value;
      return res;
    },

    'Array | Matrix': function (x) {
      return collection.deepMap(x, unaryMinus);
    }
  });

  return unaryMinus;
};