MATLAB Function Reference |

Cosine of an argument in radians

**Syntax **

**Description**

The `cos`

function operates element-wise on arrays. The function's domains and ranges include complex values. All angles are in radians.

```
Y = cos(X)
```

returns the circular cosine for each element of `X`

.

**Examples**

Graph the cosine function over the domain .

The expression `cos(pi/2)`

is not exactly zero but a value the size of the floating-point accuracy, `eps`

, because `pi`

is only a floating-point approximation to the exact value of .

**Definition**

**Algorithm**

`cos`

uses FDLIBM, which was developed at SunSoft, a Sun Microsystems, Inc. business, by Kwok C. Ng, and others. For information about FDLIBM, see http://www.netlib.org.

**See Also**

corrcoef | cosd |

© 1994-2005 The MathWorks, Inc.