Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!julius.cs.uiuc.edu!ux1.cso.uiuc.edu!uxa.cso.uiuc.edu!dslg0849
From: dslg0849@uxa.cso.uiuc.edu (Daniel S. Lewart)
Newsgroups: comp.lang.pascal
Subject: Re: Trigonometric function
Message-ID: <1990Nov1.221441.5599@ux1.cso.uiuc.edu>
Date: 1 Nov 90 22:14:41 GMT
References: <1650@marlin.NOSC.MIL>
Sender: news@ux1.cso.uiuc.edu (News)
Organization: University of Illinois at Urbana
Lines: 18

evansjr@marlin.NOSC.MIL (John R. Evans) writes:
>	I would like to use the "arccos" function---but it is
>	not standard pascal.
>	Is there a simple way to do this using standard pascal
>	functions such as arctan,sin, or cos?

function ArcCos(x: Real): Real;
begin
  if x > 0 then
    ArcCos := ArcTan( Sqrt(1-Sqr(x))/x )
  else if x < 0 then
    ArcCos := ArcTan( Sqrt(1-Sqr(x))/x ) + Pi
  else
    ArcCos := Pi/2;
end;

Daniel Lewart
d-lewart@uiuc.edu