Re: Arithmetic simplification

*To*: mathgroup at smc.vnet.net*Subject*: [mg26222] Re: Arithmetic simplification*From*: "Paul Lutus" <nospam at nosite.com>*Date*: Sun, 3 Dec 2000 18:05:54 -0500 (EST)*References*: <90a7o4$e8t@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

"Adalbert Hanssen" <hanssen at zeiss.de> wrote in message news:90a7o4$e8t at smc.vnet.net... > Hi, MathGroup, > > why does Mathematica return this sample expression unchanged > (it can easily be simplified to 0, as the second > part is just the first half with 1/3 factored out)? > > o30/3+(dw2*o46)/(3*o55)+o55/(3*dw2) - (o30+(dw2*o46)/o55+o55/dw2)/3 > > Of course, in this case Simplify, Expand or Together > find, that this is 0. This is only a sniplet from > a larger expression with a dozen of ohter variables, > indeed, o33, o46 and o55 are themselves expressions > involving several other variables. > > I tried to simplify the large expression by hand > (i.e. factor out common factors from partial sums > etc) and I used Mathematica to check, if I did it > right. However, in several cases, Together, > PowerExpand and Simlify took "forever" after > I did simplifications of the above kind. > > Is there a way to first apply Together etc > only to Arguments of Sqrt, Power etc, > in particular first to those Sqrt, Power etc, > which are nested most deeply and apply thm > to the higher ones after that? I'd like to be able to help you, but Mathematica 4.0's result is: In[1]:= Simplify[o30/3 + (dw2*o46)/(3*o55) + o55/(3*dw2) - (o30 + (dw2*o46)/o55 + o55/dw2)/3] Out[1]= 0 I guess it helps to include the version of Mathematica you are using. :) -- Paul Lutus www.arachnoid.com