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RE: Re: Question about Replace

  • To: mathgroup at smc.vnet.net
  • Subject: [mg35712] RE: [mg35689] Re: [mg35670] Question about Replace
  • From: "DrBob" <majort at cox-internet.com>
  • Date: Sat, 27 Jul 2002 06:43:12 -0400 (EDT)
  • Reply-to: <drbob at bigfoot.com>
  • Sender: owner-wri-mathgroup at wolfram.com

What you want is a change of variables:

expr = x + y + z/(x + y) + e^(x + y) + (w*x) + y;
expr /. x -> z - y /. z -> x

1 + e^x + x + w*(x - y) + y

Bobby Treat

-----Original Message-----
From: Xuguang(Heather) Zhang [mailto:xuguang_zhang at hotmail.com] 
To: mathgroup at smc.vnet.net
Subject: [mg35712] [mg35689] Re: [mg35670] Question about Replace

Hi, Bob,

I tried ReplaceRepeated, however, I got the following answer:
x+y+z/(x+y)+e^(x+y)+(w*x)+y//. x+y->x

e^x+x+(w*x)+2y+z/x

In fact, there is still one more (x+y) term if we rewritten the answer.
That
is e^x+(x+y)+y+(w*x)+z/x. Do you know how to get rid of it? Thanks.


----- Original Message -----
From: <BobHanlon at aol.com>
To: mathgroup at smc.vnet.net
Subject: [mg35712] [mg35689] Re: [mg35670] Question about Replace


>
> In a message dated 7/25/02 5:06:57 AM, xzhang2 at is2.dal.ca writes:
>
> >I have an expression: x+y+z/(x+y)+e^(x+y)+w*x+y.... I want to replace
> >any (x+y) term by x no matter how the expression looks like.  I tried
> >"/."command. However, it does not work properly. Is there any simple
way
> >of doing this?
>
> Use ReplaceRepeated
>
> x+y+z/(x+y)+e^(x+y)+w*(x+y) //. x+y->x
>
> e^x + w*x + x + z/x
>
>
> Bob Hanlon
> Chantilly, VA  USA
>
>






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