# cos

Returns the cosine of `a` (input in radians).

## Syntax

R = cos(a)

## Inputs

`a`- Any valid scalar | vector | matrix in radians.

## Outputs

- R
- scalar | vector | matrix

## Examples

Simple scalar
input:

`R = cos(-0.5)`

`R = 0.877583`

Simple matrix
input:

`R = cos([-3,.6])`

`R = [ -0.989992 0.825336 ]`

Complex matrix
input:

`R = cos([i+2,3i-1;i,0.3])`

`R = [ -0.642148-1.06861i, 5.43958 + 8.42975i; 1.54308, 0.955336]`