# Swift - atan2() Function

The Swift atan2() function returns the angle theta from the conversion of rectangular coordinates (x, y) to polar coordinates (r, theta). The returned value will be in the range -𝜋 through 𝜋.

### Syntax

In Foundation framework, it is defined as follows:

```public func atan2(_ __y: Double, _ __x: Double) -> Double
```

### Parameters

 `y` Specify the ordinate coordinate. `x` Specify the abscissa coordinate.

### Return Value

Returns theta of the point (r, theta) in polar coordinates that corresponds to the point (x, y) in Cartesian coordinates.

### Example:

In the example below, atan2() function is used to calculate the theta of a point.

```import Foundation

print("atan2(1.0, 1.0) = \(atan2(1.0, 1.0))")
print("atan2(1.0, 2.0) = \(atan2(1.0, 2.0))")
print("atan2(2.0, 1.0) = \(atan2(2.0, 1.0))")
print("atan2(-1.0, 2.0) = \(atan2(-1.0, 2.0))")
print("atan2(-1.0, -2.0) = \(atan2(-1.0, -2.0))")
```

The output of the above code will be:

```atan2(1.0, 1.0) = 0.7853981633974483
atan2(1.0, 2.0) = 0.4636476090008061
atan2(2.0, 1.0) = 1.1071487177940904
atan2(-1.0, 2.0) = -0.4636476090008061
atan2(-1.0, -2.0) = -2.677945044588987
```

❮ Swift Math Functions

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