Services & Resources / Wolfram Forums
MathGroup Archive
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2003

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

Search the Archive

Re: Simplify[Abs[x],x<0]]

  • To: mathgroup at
  • Subject: [mg39323] Re: Simplify[Abs[x],x<0]]
  • From: "Allan Hayes" <hay at>
  • Date: Tue, 11 Feb 2003 04:42:08 -0500 (EST)
  • References: <b27fp8$na4$>
  • Sender: owner-wri-mathgroup at

"Uri Zwick" <zwick at> wrote in message
news:b27fp8$na4$1 at
> Hi,
> Simplify[ Abs[x] , x>0 ] returns x.
> But, Simplify[ Abs[x] , x<0] returns Abs[x], and not -x.
> Why is that?
> Uri

Mathematica considers Abs[x] to be less complex than -x:




        Times[-1, x]

So we have to tell it what our measure of complexity is:

    Simplify[Abs[x],x<0 ,



Allan Hayes
Mathematica Training and Consulting
Leicester UK
hay at
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565

  • Prev by Date: Re: Large lists problem...
  • Next by Date: Re: I need some help about this error
  • Previous by thread: Re: Simplify[Abs[x],x<0]]
  • Next by thread: RE: Simplify[Abs[x],x<0]]