mathjs/src/function/trigonometry/cos.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 cosine of a value.
   *
   * For matrices, the function is evaluated element wise.
   *
   * Syntax:
   *
   *    math.cos(x)
   *
   * Examples:
   *
   *    math.cos(2)                      // returns number -0.4161468365471422
   *    math.cos(math.pi / 4)            // returns number  0.7071067811865475
   *    math.cos(math.unit(180, 'deg'))  // returns number -1
   *    math.cos(math.unit(60, 'deg'))   // returns number  0.5
   *
   *    const angle = 0.2
   *    math.pow(math.sin(angle), 2) + math.pow(math.cos(angle), 2) // returns number ~1
   *
   * See also:
   *
   *    cos, tan
   *
   * @param {number | BigNumber | Complex | Unit | Array | Matrix} x  Function input
   * @return {number | BigNumber | Complex | Array | Matrix} Cosine of x
   */
  const cos = typed('cos', {
    'number': Math.cos,

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

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

    'Unit': function (x) {
      if (!x.hasBase(type.Unit.BASE_UNITS.ANGLE)) {
        throw new TypeError('Unit in function cos is no angle')
      }
      return cos(x.value)
    },

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

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

  return cos
}

exports.name = 'cos'
exports.factory = factory