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Re: Re: Simplify stuck in simple expression

• To: mathgroup at smc.vnet.net
• Subject: [mg50204] Re: [mg50178] Re: Simplify stuck in simple expression
• From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
• Date: Fri, 20 Aug 2004 04:57:54 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

On Thursday, August 19, 2004, at 11:28 AM, Carlos Felippa wrote:

> Andrzej Kozlowski <akoz at mimuw.edu.pl> wrote in message 
> news:<cfv4hu$8jd$1 at smc.vnet.net>...
>> You can use:
>>
>>
>> FullSimplify[Factor //@ ((2 - Sqrt[72*(1 + a*b)^2 + 4])/
>>      (2*a))]
>>
>>
>> (1 - Sqrt[18*a*b*(a*b + 2) + 19])/a
>>
>>
>> However, as this has the same LeafCount as the expression you desire
>> you, would need to find a suitable ComplexityFunction to obtain the
>> answer you want.
>>
>>
> My objective has a smaller LeafCount:
>
>  Print[LeafCount[(2 - Sqrt[72*(1 + a*b)^2 + 4])/ (2*a)]];
>
>  26
>
>  Print[LeafCount[(1 - Sqrt[18*(1 + a*b)^2 + 1])/ a]]
>
>  23
>
>
>
But   it is not smaller than the answer returned by the  method I 
proposed, which of course was the point I was making:

In[1]:=
LeafCount[(1-Sqrt[18*a*b*(a*b+2)+19])/a]

Out[1]=
23


Andrzej