       Re: Replacement

• To: mathgroup at smc.vnet.net
• Subject: [mg4422] Re: Replacement
• From: wagner at motel6.cs.colorado.edu (Dave Wagner)
• Date: Mon, 22 Jul 1996 00:09:22 -0400
• Organization: University of Colorado, Boulder
• Sender: owner-wri-mathgroup at wolfram.com

```Whoops, in my previous post I gave the wrong output:

In article <4snbf1\$rra at dragonfly.wolfram.com>,
Dave Wagner <wagner at motel6.cs.colorado.edu> wrote:
>In article <4shud7\$g7n at ralph.vnet.net>,
>Sergej Gerassimov <ges at vsnhdd.cern.ch> wrote:
>>
>>x/Sqrt[a^2+b^2]+Sqrt[a^2+b^2]/y //. Sqrt[a^2+b^2]->r
>>gives:
>>
>>      x         r
>>------------- + -
>>Sqrt[a^2+b^2]   y
>>
>>How to replace Sqrt[a^2+b^2] by r everywhere in the expression?
>
>A general solution to this type of problem is to introduce a dummy
>variable and use Solve:
>
>    In:=
>    Solve[{dummy==x/Sqrt[a^2+b^2]+Sqrt[a^2+b^2]/y, r==Sqrt[a^2+b^2]},
>	  {dummy},{a,b}]
>
>    Out=
>	  x         r
>    ------------- + -
>	  2    2    y
>    Sqrt[a  + b ]

That output should have been:

Out=
x   r
{{dummy -> - + -}}
r   y

I was cutting and pasting all over the place and I must have inadvertently
included the wrong output in my post.

Sorry for any confusion.

Dave Wagner
Principia Consulting
(303) 786-8371
dbwagner at princon.com
http://www.princon.com/princon

==== [MESSAGE SEPARATOR] ====

```

• Prev by Date: Re: Pentium Performance
• Next by Date: Re: bar charts with error bars?
• Previous by thread: Pentium Performance