mathjs/src/function/trigonometry/acos.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) {
  /**
   * Calculate the inverse cosine of a value.
   *
   * For matrices, the function is evaluated element wise.
   *
   * Syntax:
   *
   *    math.acos(x)
   *
   * Examples:
   *
   *    math.acos(0.5)           // returns number 1.0471975511965979
   *    math.acos(math.cos(1.5)) // returns number 1.5
   *
   *    math.acos(2)             // returns Complex 0 + 1.3169578969248166 i
   *
   * See also:
   *
   *    cos, atan, asin
   *
   * @param {number | BigNumber | Complex | Array | Matrix} x  Function input
   * @return {number | BigNumber | Complex | Array | Matrix} The arc cosine of x
   */
  const acos = typed('acos', {
    'number': function (x) {
      if ((x >= -1 && x <= 1) || config.predictable) {
        return Math.acos(x)
      } else {
        return new type.Complex(x, 0).acos()
      }
    },

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

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

    'Array | Matrix': function (x) {
      return deepMap(x, acos)
    }
  })

  acos.toTex = { 1: `\\cos^{-1}\\left(\${args[0]}\\right)` }

  return acos
}

exports.name = 'acos'
exports.factory = factory