double
     atan(double x);

     long double
     atanl(long double x);

     float
     atanf(float x);

DESCRIPTION

     The atan() function computes the principal value of the arc tangent of x.
     The result is in the range [-pi/2, +pi/2].

SPECIAL VALUES

     atan(+-0) returns +-0.

     atan(+-infinity) returns +-pi/2

SEE ALSO

     acos(3), asin(3), atan2(3), cos(3), cosh(3), sin(3), sinh(3), tan(3),
     tanh(3), math(3) The atan() function conforms to ISO/IEC 9899:1999(E).

BSD                            November 18, 2002                           BSD