Re: Re: Re: Radicals simplify

*To*: mathgroup at smc.vnet.net*Subject*: [mg106415] Re: [mg106411] Re: [mg106386] Re: Radicals simplify*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Tue, 12 Jan 2010 04:46:59 -0500 (EST)*References*: <hic37h$5ef$1@smc.vnet.net> <201001111030.FAA23508@smc.vnet.net> <201001112354.SAA21089@smc.vnet.net>

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 >

**Follow-Ups**:**Re: Re: Re: Re: Radicals simplify***From:*Murray Eisenberg <murray@math.umass.edu>

**References**:**Re: Radicals simplify***From:*dh <dh@metrohm.com>

**Re: Re: Radicals simplify***From:*Murray Eisenberg <murray@math.umass.edu>