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MathGroup Archive 2005

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Re: Re: Eliminating Annoying Minus Signs

  • To: mathgroup at smc.vnet.net
  • Subject: [mg58779] Re: [mg58770] Re: [mg58756] Eliminating Annoying Minus Signs
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Mon, 18 Jul 2005 03:21:18 -0400 (EDT)
  • Reply-to: hanlonr at cox.net
  • Sender: owner-wri-mathgroup at wolfram.com

The attributes are documented,  use ?? to see them:

??Numerator

??Denominator


Bob Hanlon

> 
> From: yehuda ben-shimol <bsyehuda at gmail.com>
To: mathgroup at smc.vnet.net
> Date: 2005/07/17 Sun PM 01:03:15 EDT
> Subject: [mg58779] [mg58770] Re: [mg58756] Eliminating Annoying Minus Signs
> 
> 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
> > 
> >
> 
> 


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