Re: Eliminating Annoying Minus Signs

*To*: mathgroup at smc.vnet.net*Subject*: [mg58770] Re: [mg58756] Eliminating Annoying Minus Signs*From*: yehuda ben-shimol <bsyehuda at gmail.com>*Date*: Sun, 17 Jul 2005 13:03:15 -0400 (EDT)*References*: <76e8f81805071705503c70daa4@mail.gmail.com> <NDBBJGNHKLMPLILOIPPOIEHEEJAA.djmp@earthlink.net>*Reply-to*: yehuda ben-shimol <bsyehuda at gmail.com>*Sender*: owner-wri-mathgroup at wolfram.com

Hi David, Although not documented it seems that both Numerator and Denominator are listable so (-Numerator[#])/(-Denominator[#])&[test] or test//(-Numerator[#])/(-Denominator[#])& will do the same without mapping. yehuda On 7/17/05, David Park <djmp at earthlink.net> wrote: > Yehuda, > > Thanks. That seems pretty good. > > We could turn this into a routine that could be mapped onto terms more > generally in an expression. > > NDSignSwitch = (-Numerator[#])/(-Denominator[#]) &; > > test = {-((2*x)/(-1 + z)), -((2*y)/(-1 + z)), -1}; > > NDSignSwitch /@ test > {(2*x)/(1 - z), (2*y)/(1 - z), -1} > > David Park > djmp at earthlink.net > http://home.earthlink.net/~djmp/ > > > > From: yehuda ben-shimol [mailto:bsyehuda at gmail.com] To: mathgroup at smc.vnet.net > > 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 > >