mathjs/src/function/arithmetic/unaryMinus.js

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser with support for symbolic computation, comes with a large set of built-in functions and constants, and offers an integrated solution to work with dif

'use strict'

const deepMap = require('../../utils/collection/deepMap')

function factory (type, config, load, typed) {
  const latex = require('../../utils/latex')

  /**
   * 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 | Fraction | Complex | Unit | Array | Matrix} x Number to be inverted.
   * @return {number | BigNumber | Fraction | Complex | Unit | Array | Matrix} Returns the value with inverted sign.
   */
  const unaryMinus = typed('unaryMinus', {
    'number': function (x) {
      return -x
    },

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

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

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

    'Unit': function (x) {
      const res = x.clone()
      res.value = unaryMinus(x.value)
      return res
    },

    'Array | Matrix': function (x) {
      // deep map collection, skip zeros since unaryMinus(0) = 0
      return deepMap(x, unaryMinus, true)
    }

    // TODO: add support for string
  })

  unaryMinus.toTex = {
    1: `${latex.operators['unaryMinus']}\\left(\${args[0]}\\right)`
  }

  return unaryMinus
}

exports.name = 'unaryMinus'
exports.factory = factory