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

NAME
     atan, atanf, atanl - arc tangent functions of one variable

SYNOPSIS
     #include <math.h>

     double
     atan(double x);

     float
     atanf(float x);

     long double
     atanl(long double x);

DESCRIPTION
     The atan() function computes the principal value of the arc tangent of x
     in the range [-pi/2, +pi/2].  The atanf() function is a single precision
     version of atan().  The atanl() function is an extended precision version
     of atan().

SEE ALSO
     acos(3), asin(3), atan2(3), cos(3), cosh(3), math(3), sin(3), sinh(3),
     tan(3), tanh(3)

OpenBSD 4.9                    December 12, 2008                   OpenBSD 4.9