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MathGroup Archive 2003

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Re: Trigonometric math functions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg44569] Re: Trigonometric math functions
  • From: poujadej at yahoo.fr (Jean-Claude Poujade)
  • Date: Fri, 14 Nov 2003 04:43:16 -0500 (EST)
  • References: <boig47$og2$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

"Bruno" <bpa at BPASoftware.com> wrote in message news:<boig47$og2$1 at smc.vnet.net>...
> Hi all,
> 
> I would like to implement an arc cos function on a 16 bits µcontroller
> (optimized sin() and cos() function are welcome).
> 
> Does someone have some sources or an algorythm in this way ?
> 
> Thanks in advance,
> 
> Regards.

Why not simply use a series expansion?

In[1]:=Series[ArcCos[x],{x,0,3}]//Normal 
Out[1]=Pi/2 - x - x^3/6
In[2]:=acos[0]=Pi/2;
       acos[1]=0;
       acos[x_ /; 0<x<1] := Pi/2-x-x^3/6  ;
       acos[x_ /; x<0] := Pi-acos[-x];
In[3]:=Plot[{ArcCos[x],acos[x]},{x,-1,1}]
No difference can be seen with a naked eye!
---
jcp


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