ATAN Section: Linux Programmer's Manual (3) Updated: June 8, 2025 Index   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   Index NAME SYNOPSIS DESCRIPTION RETURN VALUE CONFORMING TO SEE ALSO This document was created by using the manual pages. Time: 11:58:02 GMT, March 24, 2025