---
name: "ctanl"
section: "3"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/ctan/3"
---

# ctanl(3)

complex tangent function

Part of [ctan(3)](/ctan/3.md).

## NAME

ctan, ctanf, ctanl - complex tangent function

## LIBRARY

Math library (*libm*, *-lm*)

## SYNOPSIS

```
#include <complex.h>
```

**double complex ctan(double complex** *z***);** **float complex ctanf(float complex** *z***);** **long double complex ctanl(long double complex** *z***);**

## DESCRIPTION

These functions calculate the complex tangent of *z*.

The complex tangent function is defined as:

```
ctan(z) = csin(z) / ccos(z)
```

## ATTRIBUTES

For an explanation of the terms used in this section, see [**attributes**(7)](/attributes/7.md).

| | | |
| --- | --- | --- |
| **Interface** | **Attribute** | **Value** |
| **ctan**(), **ctanf**(), **ctanl**() | Thread safety | MT-Safe |

## STANDARDS

C11, POSIX.1-2008.

## HISTORY

glibc 2.1. C99, POSIX.1-2001.

## SEE ALSO

[**cabs**(3)](/cabs/3.md), [**catan**(3)](/catan/3.md), [**ccos**(3)](/ccos/3.md), [**csin**(3)](/csin/3.md), [**complex**(7)](/complex/7.md)