Arc tangent

# atan

(PHP 4, PHP 5, PHP 7, PHP 8)

atan — Arc tangent

### Description

atan(float `$num`): float

Returns the arc tangent of `num` in radians. atan() is the inverse function of tan(), which means that `$num == tan(atan($num))` for every value of `num` that is in the domain of atan().

### Parameters

`num`

  The argument to process

### Return Values

The arc tangent of `num` in radians.

### See Also

- tan() - Tangent
- atanh() - Inverse hyperbolic tangent
- asin() - Arc sine
- acos() - Arc cosine

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