Calculate arcus tangent defined on whole circle.

a | The denumerator. |

b | The numerator. |

return value | The corrected angle atan(b/a). |

Based on signs of *a* and *b*, the exact quarter of the circle for the angle can be calculated. The*atan2* calculates *atan(b/a)*, and corrects its angle.

The arguments can only be real numbers or quantities with same unit.

```
atan2(
```*-1*, *-1*) as degrees