#
ATN() Function - Arctangent

## Syntax

ATN(num{,precis}{,ERR=lineref})

## Description

The ATN() function returns the arctangent of num. The result is in radians and is in the range -pi/2 to pi/2.

Parameter |
Description |
---|---|

num |
Number to be processed. |

precis |
Numeric precision, an integer in the range of 1 to 16 (default is 6). This represents the number of decimal places desired in the result. Because PRO/5 uses 16-digit decimal arithmetic, it could be difficult to compute a 16-digit precision ATN(). Because this is not required by most applications, an alternate precision may be much more efficient. |

ERR=lineref |
Branch to be taken if an error occurs during execution. |

## Examples

1000 LET A=ATN(3.14159)

2000 LET A=ATN(B,16); REM - MAXIMUM PRECISION