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Re: Re: Re: Radicals simplify
Yes, but Adam Strzebonski has already posted here the default
CoplexityFunction in the past, and knowing it really wont help you much:
SimplifyCount[p_] :=
If[Head[p]===Symbol, 1,
If[IntegerQ[p],
If[p==0, 1, Floor[N[Log[2, Abs[p]]/Log[2, 10]]]+If[p>0, 1,
2]],
If[Head[p]===Rational,
SimplifyCount[Numerator[p]]+SimplifyCount[Denominator[p]]+1,
If[Head[p]===Complex,
SimplifyCount[Re[p]]+SimplifyCount[Im[p]]+1,
If[NumberQ[p], 2,
SimplifyCount[Head[p]]+If[Length[p]==0, 0,
Plus@@(SimplifyCount/@(List@@p))]]]]]]
Would it be helpful to have this in the Documentation? Or is it more
helpful to know that most of the time (but not always) this agrees with
LeafCount?
I think a very large percentage of complaints about the documentation
reduce to this sort of issues.
Andrzej Kozlowski
On 12 Jan 2010, at 08:54, Murray Eisenberg wrote:
> 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)
>>
>>>
>>
>>> Thanks in advanced.
>>
>>>
>>
>>>
>>
>>>
>>
>>>
>>
>>>
>>
>>>
>>
>>>
>>
>>
>>
>
> --
> 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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