ATAN(3)            Linux Programmer's Manual            ATAN(3)





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);


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.  The  float  and  long
       double variants are C99 requirements.

SEE ALSO
       acos(3), asin(3), atan2(3), cos(3), sin(3), tan(3)



                           2002-07-27                   ATAN(3)
