Path: utzoo!attcan!uunet!auspex!guy
From: guy@auspex.UUCP (Guy Harris)
Newsgroups: comp.windows.news
Subject: Re: problems with NeWS stuff on SUG tape
Message-ID: <667@auspex.UUCP>
Date: 10 Dec 88 04:47:35 GMT
References: <8812090152.AA19052@brillig.umd.edu>
Reply-To: guy@auspex.UUCP (Guy Harris)
Organization: Auspex Systems, Santa Clara
Lines: 27

>	Also, Bruce Schwartz's NewsDraw program fails to link on
>our SunOS 3.4 system.  The unresolved reference is to sincos.  Because
>sincos is no doubt in the SunOS 4.0 math library, can someone please
>send me a description of what it does.

From the 4.0 TRIG(3M):

     void sincos(x, s, c)
     double x, *s, *c;

	...

     sin, cos, sincos, and tan() return  trigonometric  functions
     of  radian arguments.  The values of trigonometric functions
     of arguments exceeding pi/4 in magnitude are affected by the
     precision  of the approximation to pi2 used to reduce those
     arguments to the range -pi/4 to  pi/4.   Argument  reduction
     may occur in hardware or software; if in software, the vari-
     able fp_pi defined in <math.h> allows changing  that  preci-
     sion  at run time.  Trigonometric argument reduction is dis-
     cussed in the Floating Point Programmers Guide.   Note  that
     sincos(x,s,c) allows simultaneous computation of *s = sin(x)
     and *c = cos(x).

It shouldn't have been used, or at least its use should have been
#ifdeffed; it's an optimization, and "sincos" isn't present on every
system (probably not even on every system that runs NeWS).