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Re: FullSimplify failure

  • To: mathgroup at smc.vnet.net
  • Subject: [mg38498] Re: FullSimplify failure
  • From: "Allan Hayes" <hay at haystack.demon.co.uk>
  • Date: Fri, 20 Dec 2002 04:25:49 -0500 (EST)
  • References: <atp730$90o$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

"Carlos Felippa" <carlos at colorado.edu> wrote in message
news:atp730$90o$1 at smc.vnet.net...
> Print[ FullSimplify[ArcCos[(Sqrt[3]-1)/(2*Sqrt[2])]]//InputForm];
> Print[ FullSimplify[ArcSin[(Sqrt[2]+Sqrt[6])/4]]//InputForm];
>
> (5*Pi)/12
>
> ArcSin[(Sqrt[2] + Sqrt[6])/4]
>
>
> Both answers should be 5*Pi/12.  This is fouling up a script.
> Is there a way to get FullSimplify to do exactly that for
> the ArcSin?
>
> Carlos Felippa
>

Carlos,

We can use a suitable complexity function:

    InputForm[FullSimplify[ArcCos[(Sqrt[3] - 1)/(2*Sqrt[2])],
       ComplexityFunction -> (Count[#1, _Sqrt, Infinity] & )]]

        (5*Pi)/12

   InputForm[FullSimplify[ArcSin[(Sqrt[2] + Sqrt[6])/4],
       ComplexityFunction -> (Count[#1, _Sqrt, Infinity] & )]]

        (5*Pi)/12

But why this should be needed here I can't see.


Allan

---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565





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