Description: | Produces an arctangent. The result is the principal value of the argument of the nonzero complex number (X, Y). | ||

Class: |
Elemental function; Generic | ||

Arguments: |
Y | Must be of type real. | |

X | Must have the same type and kind parameters as Y. If Y has the value zero, X cannot have the value zero. | ||

Results: | The result
type is the same as X and is
expressed in radians. The value lies in the range -pi < ATAN2 (Y, X) <= pi.
If X /= zero, the result is approximately equal to the value of arctan (Y/X).
If Y > zero, the result is positive. If Y < zero, the result is negative. If Y = zero, the result is zero (if X > zero) or pi (if X < zero). If X = zero, the absolute value of the result is pi/2. |

Specific Name | Argument Type | Result Type |
---|---|---|

ATAN2 | REAL(4) | REAL(4) |

DATAN2 | REAL(8) | REAL(8) |

QATAN2 | REAL(16) | REAL(16) |

**Examples**

ATAN2 (2.679676, 1.0) has the value 1.213623.

If Y has the value

```
[ 1 1 ]
[ -1 -1 ]
```

and X has the value
```
[ -1 1 ]
[ -1 1 ],
```

then ATAN2 (Y, X) is

Previous Page Next Page Table of Contents