Math.cosh()

The Math.cosh() function returns the hyperbolic cosine of a number, that can be expressed using the constant e:

Math.cosh(x) = e x + e - x 2 \mathtt{\operatorname{Math.cosh(x)}} = \frac{e^x + e^{-x}}{2}

Syntax

Math.cosh(x)

Parameters

x
A number.

Return value

The hyperbolic cosine of the given number.

Description

Because cosh() is a static method of Math, you always use it as Math.cosh(), rather than as a method of a Math object you created (Math is not a constructor).

Examples

Using Math.cosh()

Math.cosh(0);  // 1
Math.cosh(1);  // 1.5430806348152437
Math.cosh(-1); // 1.5430806348152437

Polyfill

This can be emulated with the help of the Math.exp() function:

Math.cosh = Math.cosh || function(x) {
  return (Math.exp(x) + Math.exp(-x)) / 2;
}

or using only one call to the Math.exp() function:

Math.cosh = Math.cosh || function(x) {
  var y = Math.exp(x);
  return (y + 1 / y) / 2;
};

Specifications

Specification
ECMAScript (ECMA-262)
The definition of 'Math.cosh' in that specification.

Browser compatibility

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See also