mathjs/src/function/trigonometry/cosh.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 hyperbolic cosine of a value,
   * defined as `cosh(x) = 1/2 * (exp(x) + exp(-x))`.
   *
   * For matrices, the function is evaluated element wise.
   *
   * Syntax:
   *
   *    math.cosh(x)
   *
   * Examples:
   *
   *    math.cosh(0.5)       // returns number 1.1276259652063807
   *
   * See also:
   *
   *    sinh, tanh
   *
   * @param {number | BigNumber | Complex | Unit | Array | Matrix} x  Function input
   * @return {number | BigNumber | Complex | Array | Matrix} Hyperbolic cosine of x
   */
  const cosh = typed('cosh', {
    'number': _cosh,

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

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

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

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

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

  return cosh
}

/**
 * Calculate the hyperbolic cosine of a number
 * @param {number} x
 * @returns {number}
 * @private
 */
const _cosh = Math.cosh || function (x) {
  return (Math.exp(x) + Math.exp(-x)) / 2
}

exports.name = 'cosh'
exports.factory = factory