Re: Eliminating Annoying Minus Signs

*To*: mathgroup at smc.vnet.net*Subject*: [mg58760] Re: [mg58756] Eliminating Annoying Minus Signs*From*: yehuda ben-shimol <bsyehuda at gmail.com>*Date*: Sun, 17 Jul 2005 13:03:07 -0400 (EDT)*References*: <200507170704.DAA02676@smc.vnet.net>*Reply-to*: yehuda ben-shimol <bsyehuda at gmail.com>*Sender*: owner-wri-mathgroup at wolfram.com

Hi David, How about (- Numerator /@ test)/(- Denominator /@ test) this is not error prone. I'm almost certaint that there is more efficient way of doing this. I'll try to find it later regards yehuda On 7/17/05, David Park <djmp at earthlink.net> wrote: > Here is an expression that has annoying minus signs in it. > > test = {-((2*x)/(-1 + z)), -((2*y)/(-1 + z)), -1}; > > We can get rid of them with the following operation. > > MapAt[Minus, test, {{1, 1}, {1, 3, 1}, {2, 1}, {2, 3, 1}}] > {(2*x)/(1 - z), (2*y)/(1 - z), -1} > > But it involves ferreting out the two positions at which we want to change signs and so is a little tedious and error prone. > > Does someone have a simpler method for simplifying such expressions, which occur quite often with Mathematica? > > David Park > djmp at earthlink.net > http://home.earthlink.net/~djmp/ > >

**References**:**Eliminating Annoying Minus Signs***From:*"David Park" <djmp@earthlink.net>