ATAN(3) Linux Programmer's Manual ATAN(3)
NAME
atan - arc tangent function
SYNOPSIS
#include <math.h>
double atan(double x);
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
SVID 3, POSIX, BSD 4.3, ISO 9899
SEE ALSO
acos(3), asin(3), atan2(3), cos(3), sin(3), tan(3)
1993-06-08 ATAN(3)
