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Re: algebraic manipulation

• To: mathgroup at smc.vnet.net
• Subject: [mg22376] Re: algebraic manipulation
• From: "Allan Hayes" <hay at haystack.demon.co.uk>
• Date: Sat, 26 Feb 2000 22:05:03 -0500 (EST)
• References: <897eqv$5u3@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Peter,
Mathematica 4.0x gives


k r  Cos[k r]/(Sqrt[k]  r^3)

(Sqrt[k]*Cos[k*r])/r^2

With Mathematica 3.x you might like to try PowerExpand


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



"Peter Jay Salzman" <covenant at dirac.org> wrote in message
news:897eqv$5u3 at smc.vnet.net...
> sorry to ask such a simple question...
>
> i have a very long espression of the form
>
>  A[k, r]( B[k,r] + C[k,r] + blah blah blah)
>  ------------------------------------------
>              D[k, r]
>
> it took me awhile to figure out how to decompose this (i was trying to use
> Apart.  instead, ExpandAll seemed to do the trick).
>
> but i'm still seeing terms that look like:
>
>    k r cos(k r)
>    -------------
>    \sqrt{k} r^{3}
>
> no amount of coaxing seems to make Mathematica want to reduce this to:
>
>    \sqrt{k} \cos(k r)
>    ------------------
>           r^{2}
>
> FullSimplify just undoes ExpandAll and puts everything over a common
> denominator.   i want separate terms which are fully reduced.
>
> how can i have Mathematica aggresively reduce these individual terms?
>
> thanks!
> pete
>
>