Re: signs in the mathematica output

*To*: mathgroup at smc.vnet.net*Subject*: [mg92507] Re: signs in the mathematica output*From*: m.r at inbox.ru*Date*: Thu, 2 Oct 2008 04:35:00 -0400 (EDT)*References*: <gbulqi$lcr$1@smc.vnet.net> <gc0tp3$9hu$1@smc.vnet.net>

This might help: In[1]:= expr = (a - 1)/(s - 1) In[2]:= Module[{s}, expr /. -1 + x_ :> s (1 - x) /. s -> -1] Out[2]= (1 - a)/(1 - s) Maxim Rytin m.r at inbox.ru David Park wrote: > The handling of signs under simplification is an annoying feature of > Mathematica. > > Sometimes the result might look better if you display in TraditionalForm. > > Simplify[(1 - s) (1 - a)] > % // TraditionalForm > (-1 + a) (-1 + s) > (a - 1) (s - 1) > > Otherwise you can Map Minus onto the two factors. > > Simplify[(1 - s) (1 - a)] > Minus /@ % > (-1 + a) (-1 + s) > (1 - a) (1 - s) > > More generally what you have to do is Map Minus at the location of two > factors. For example if we divide the two factors we could use: > > Simplify[(1 - s)/(1 - a)] > MapAt[Minus, %, {{1, 1}, {2}}] > (-1 + s)/(-1 + a) > (1 - s)/(1 - a) > > But getting the positions of the two factors and straightening everything up > can be something of a pain in the neck. Maybe someone else will have a > better suggestion. > > > -- > David Park > djmpark at comcast.net > http://home.comcast.net/~djmpark/ > > > "Simone Moriconi" <simone.moriconi at eco.unipmn.it> wrote in message > news:gbulqi$lcr$1 at smc.vnet.net... > > Hello everybody! I have a problem in using the Mathematica Package which > > is probably a bit stupid but very annoying when you have long > > expressions.. > > > > When I "FullSimplify" big equations, in the output the negative sign is > > always put aside i.e. if I do something like: > > > > FullSimplify[(1-s)(1-a)] > > > > I obtain > > > > (-1+s)(-1+a). > > > > Which is very confusing with long and tedius expressions. Does anybody > > know a way to solve this problem? > > > > Thanks a lot for your help!! > >