Re: Re: how to have a blind factorization of a polinomial?

*To*: mathgroup at smc.vnet.net*Subject*: [mg54151] Re: [mg54123] Re: how to have a blind factorization of a polinomial?*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Sat, 12 Feb 2005 01:56:59 -0500 (EST)*References*: <cud789$2t3$1@smc.vnet.net> <cuf453$gfb$1@smc.vnet.net> <200502110833.DAA09170@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On 11 Feb 2005, at 08:33, foice wrote: > On Thu, 10 Feb 2005 07:57:23 +0000 (UTC), "Jens-Peer Kuska" > <kuska at informatik.uni-leipzig.de> wrote: > >> Sqrt[x + y] /. a_ + x :> x*(a/x + 1) > Thanks for your help. Probably is a viable method, but is a little > less than you expect > for a WorldWideFamous software as Mathematica. > In this way you can chose the form of the output, you can also do > mistaques typing > something like > Sqrt[x^3 + y^2] /. a_ + x :> x^3*(a/x + 1) > and mathematica will not prevent you from the error giving an output > in the form > Sqrt[x^3*(y^2/x+1)] > > Is mathematica so feature poor to allow only a "requested form" > factorization? > I can't belive it. > Why there isn't somethig as Collect but that can use also negatieve > powers to collect? > > i.e. Collect[x+y,x,Blind] giving x(1+y/x) > > Or better, at least for my task, a Mathematica command converting a > function f(x,y) into a > function f(x,y/x) (if possible) > > Thanks > Such a function does not exist because there are infinitely many similar "factorizations" that might be useful to some users but not to 99% of others. Besides, it is easy to define it yourself: CollectBlind[expr_, {x_, y_}] := Block[{ u}, MapAll[Factor, (expr /. y -> u x)] /. u -> y/x] Then CollectBlind[x + y, {x, y}] x*(y/x + 1) and also, for example, CollectBlind[x^2 + y, {x, y}] x*(x + y/x) CollectBlind[x^2 + y, {x^2, y}] x^2*(y/x^2 + 1) Andrzej Kozlowski Chiba, Japan http://www.akikoz.net/~andrzej/ http://www.mimuw.edu.pl/~akoz/

**Follow-Ups**:**Re: Re: Re: how to have a blind factorization of a polinomial?***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>

**References**:**Re: how to have a blind factorization of a polinomial?***From:*foice <NONfoiceSPAMMARE@tiscalinet.it>