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

NNAAMMEE
     aattaann - arc tangent function of one variable

SSYYNNOOPPSSIISS
     ##iinncclluuddee <<mmaatthh..hh>>

     _d_o_u_b_l_e
     aattaann(_d_o_u_b_l_e _x)

DDEESSCCRRIIPPTTIIOONN
     The aattaann() function computes the principal value of the arc tangent of _x.
     For a discussion of error due to roundoff, see math(3).

RREETTUURRNN VVAALLUUEESS
     The aattaann() function returns the arc tangent in the range [-pi/2, +pi/2]
     radians.

SSEEEE AALLSSOO
     acos(3),  asin(3),  atan2(3),  cos(3),  cosh(3),  sin(3),  sinh(3),
     tan(3),  tanh(3),  math(3),

SSTTAANNDDAARRDDSS
     The aattaann() function conforms to ANSI C3.159-1989 (``ANSI C'').

BSD Experimental                  May 2, 1991                                1






































