# atanf(3) [freebsd man page]

```ATAN(3) 						   BSD Library Functions Manual 						   ATAN(3)

NAME
atan, atanf, atanl -- arc tangent functions of one variable

LIBRARY
Math Library (libm, -lm)

SYNOPSIS
#include <math.h>

double
atan(double x);

float
atanf(float x);

long double
atanl(long double x);

DESCRIPTION
The atan(), atanf(), and atanl() functions compute the principal value of the arc tangent of x.

RETURN VALUES
These functions return the arc tangent in the range [-pi/2, +pi/2] radians.

acos(3), asin(3), atan2(3), cos(3), cosh(3), math(3), sin(3), sinh(3), tan(3), tanh(3)

STANDARDS
The atan(), atanf(), and atanl() functions conform to ISO/IEC 9899:1999 (``ISO C99'').

BSD								   July 31, 2008							       BSD```

## Check Out this Related Man Page

```ATAN(3) 						   BSD Library Functions Manual 						   ATAN(3)

NAME
atan -- arc tangent function of one variable

SYNOPSIS
#include <math.h>

double
atan(double x);

long double
atanl(long double x);

float
atanf(float x);

DESCRIPTION
The atan() function computes the principal value of the arc tangent of x.	The result is in the range [-pi/2, +pi/2].

SPECIAL VALUES
atan(+-0) returns +-0.

atan(+-infinity) returns +-pi/2

VECTOR OPERATIONS
If you need to apply the atan() function to SIMD vectors or arrays, using the following functions provided by the Accelerate.framework may
give significantly better performance:

#include <Accelerate/Accelerate.h>

vFloat vatanf(vFloat x);
void vvatanf(float *y, const float *x, const int *n);
void vvatan(double *y, const double *x, const int *n);