# cos, cosh

## Purpose

Cosine and hyperbolic cosine.

## Synopsis

    Y = cos(X)
    Y = cosh(X)

## Description

The trigonometric functions operate element-wise on matrices. Their domains and ranges include complex values. All angles are measured in radians.

`cos(X)` is the circular cosine for each element of `X`.

`cosh(X)` is the hyperbolic cosine for each element of `X`.

## Examples

    M = magic(3)

    M =
        8    1    6
        3    5    7
        4    9    2

    cos(M*pi/4) =
        1.0000      0.7071     -0.0000
       -0.7071     -0.7071      0.7071
       -1.0000      0.7071      0.0000

`cos(pi/2)` is not exactly zero, but rather a value the size of the floating-point accuracy, `eps`, because `pi` is not exactly equal to pi .

## Algorithm

## See Also

    acos, asin, atan, exp, expm, funm, sin, tan

(c) Copyright 1994 by The MathWorks, Inc.