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man pages section 3: Extended Library Functions, Volume 2

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Updated: Thursday, June 13, 2019
 
 

atanl(3M)

Name

atan, atanf, atanl - arc tangent function

Synopsis

c99 [ flag... ] file... –lm [ library... ]
#include <math.h>

double atan(double x);
float atanf(float x);
long double atanl(long double x);

Description

These functions compute the principal value of the arc tangent of x.

Return Values

Upon successful completion, these functions return the arc tangent of x in the range [−π/2,π/2] radians.

If x is NaN, NaN is returned.

If x is ±0, x is returned.

If x is ±Inf, ±π/2 is returned.

Errors

No errors are defined.

Attributes

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Interface Stability
Committed
Availability
system/library/math
MT-Level
MT-Safe
Standard

See Also

math.h(3HEAD), atan2(3M), isnan(3M), tan(3M), attributes(7), standards(7)