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



NAME
       atan, atanf, atanl - arc tangent function

SYNOPSIS
       #include <&lt;math.h>&gt;

       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)

COLOPHON
       This page is part of release 3.05 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.



                                  2002-07-27                           ATAN(3)