• To: mathgroup at smc.vnet.net
• Subject: [mg106411] Re: [mg106386] Re: Radicals simplify
• From: Murray Eisenberg <murray at math.umass.edu>
• Date: Mon, 11 Jan 2010 18:54:14 -0500 (EST)
• Organization: Mathematics & Statistics, Univ. of Mass./Amherst
• References: <hic37h\$5ef\$1@smc.vnet.net> <201001111030.FAA23508@smc.vnet.net>

```Mathematica 7 documentation does NOT say that LeafCount is the criterion
for determining simplicity, that is, the default value of
ComplexityFunction.  Rather it says:

"The default ComplexityFunction counts the subexpressions and digits
of integers."

But it does not even say how it combines the counts of the number of
subexpressions and digits of integers!

On 1/11/2010 5:30 AM, dh wrote:
> Hi,
>
> why do you think x(x^2 y^3)^(1/4) is simpler than (x^6 y^3)^(1/4)?
>
> Mathematica needs some criterion for this decision. The default criterion is the
>
> "LeafCount[..]". If that does not suit you, you must define another
>
> criterion.
>
> Daniel
>
>
>
> francix wrote:
>
>> Hi,
>
>> I am using Matematica 7 and need some help with Radicals.
>
>>
>
>> If I do
>
>> Simplify[(x^4 y^3)^(1/4), x>= 0] I correctly have
>
>>
>
>> x (y^3)^(1/4)
>
>>
>
>> But If I do
>
>>
>
>> Simplify[(x^6 y^3)^(1/4), x>= 0] I get
>
>>
>
>> (x^6 y^3)^(1/4) and not the correct answer  x(x^2 y^3)^(1/4)
>
>>
>
>
>>
>
>>
>
>>
>
>>
>
>>
>
>>
>
>>
>
>
>

--
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305

```

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