atan(3) - Linux man page
Name
atan, atanf, atanl - arc tangent function
Synopsis
#include <math.h>
double atan(double x);
float atanf(float x);
long double atanl( long double x);
Link with -lm.
Description
The
atan() function calculates the arc tangent of
x; that is the value whose tangent is
x.
Return Value
The
atan() function returns the arc tangent in radians and the value is mathematically defined to
be between -PI/2 and PI/2 (inclusive).
Conforming to
SVr4, POSIX.1-2001, 4.3BSD, C89. The
float and
long double variants are C99 requirements.
See Also
acos(3),
asin(3),
atan2(3),
carg(3),
catan(3),
cos(3),
sin(3),
tan(3)
