Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2005
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2005

[Date Index] [Thread Index] [Author Index]

Search the Archive

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/
> 
>


  • Prev by Date: Re: Improper use of slot
  • Next by Date: Re: Eliminating Annoying Minus Signs
  • Previous by thread: Eliminating Annoying Minus Signs
  • Next by thread: Re: Eliminating Annoying Minus Signs