1*61283Sbostic.\" Copyright (c) 1991, 1993 2*61283Sbostic.\" The Regents of the University of California. All rights reserved. 348919Scael.\" 448919Scael.\" %sccs.include.redist.man% 548919Scael.\" 6*61283Sbostic.\" @(#)atan.3 8.1 (Berkeley) 06/04/93 748919Scael.\" 848919Scael.Dd 948919Scael.Dt ATAN 3 1048919Scael.Os 1148919Scael.Sh NAME 1248919Scael.Nm atan 1348919Scael.Nd arc tangent function of one variable 1448919Scael.Sh SYNOPSIS 1548919Scael.Fd #include <math.h> 1648919Scael.Ft double 1748919Scael.Fn atan "double x" 1848919Scael.Sh DESCRIPTION 1948919ScaelThe 2048919Scael.Fn atan 2148919Scaelfunction computes the principal value of the arc tangent of 2248919Scael.Fa x . 2348919ScaelFor a discussion of error due to roundoff, see 2448919Scael.Xr math 3 . 2548919Scael.Sh RETURN VALUES 2648919ScaelThe 2748919Scael.Fn atan 2848919Scaelfunction returns the arc tangent in the range 2948919Scael.Bk -words 3048919Scael.Bq -\*(Pi/2 , +\*(Pi/2 3148919Scael.Ek 3248919Scaelradians. 3348919Scael.Sh SEE ALSO 3448919Scael.Xr acos 3 , 3548919Scael.Xr asin 3 , 3648919Scael.Xr atan2 3 , 3748919Scael.Xr cos 3 , 3848919Scael.Xr cosh 3 , 3948919Scael.Xr sin 3 , 4048919Scael.Xr sinh 3 , 4148919Scael.Xr tan 3 , 4248919Scael.Xr tanh 3 , 4348919Scael.Xr math 3 , 4448919Scael.Sh STANDARDS 4548919ScaelThe 4648919Scael.Fn atan 4748919Scaelfunction conforms to 4848919Scael.St -ansiC . 49