# _ATAN2

Revision as of 13:26, 5 September 2017 by imported>SMcNeill (-)

The _ATAN2 function returns the radian angle between the positive x-axis of a plane and the point given by the coordinates (x, y).

## Syntax

*angle!*= _ATAN2(*y*,*x*)

## Parameters

*y*is the vertical axis position (row) as a positive, zero or negative floating point value.*x*is the horizontal axis position (column) as a positive, zero or negative floating point value.

## Description

- The DOUBLE radian angle returned is
**positive**for upper row values where y > 0.

- The DOUBLE radian angle returned is 0 when x > 0 and _PI when x < 0 where y = 0
- The DOUBLE radian angle returned is
**negative**for lower row values where y < 0.

- _ATAN2(0, 0) is undefined and the function returns 0 instead of a division error.

### Errors

## See also

- ATN (arctangent)
- _PI (QB64 function)
- Mathematical Operations
- Atan2 reference

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