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MathGroup Archive 2002

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Re: Peculiar output from DSolve

  • To: mathgroup at smc.vnet.net
  • Subject: [mg37015] Re: [mg36994] Peculiar output from DSolve
  • From: Selwyn Hollis <selwynh at earthlink.net>
  • Date: Sun, 6 Oct 2002 05:33:16 -0400 (EDT)
  • References: <d7.1e734c25.2acec78b@aol.com>
  • Sender: owner-wri-mathgroup at wolfram.com

I'm only a little embarassed for not having realized what was happening. 
(Perhaps I should have slept on it.)

Surely I'm not alone in thinking this symbolism is highly nonintuitive. 
But of course, for it to be otherwise would require another protected 
symbol...

---
Selwyn


BobHanlon at aol.com wrote:
> In a message dated 10/4/2002 5:13:02 AM, selwynh at earthlink.net writes:
> 
> 
>>In:  DSolve[y*D[u[x, y],x] == x*D[u[x, y],y], u[x,y], {x, y}]
>>
>>Out:  {{u[x, y] -> C[1][(1/2)*(x^2 + y^2)]}}
>>
>>Square brackets are used as grouping symbols in the result!??  :^O
>>
>>Somebody say it isn't so.
>>
> 
> 
> "It isn't so"
> 
> The square bracket is not delineating a factor it is enclosing the argument 
> to an arbitrary function named C[1].  While the function is dependent on both 
> x and y the dependence only occurs in the combination (x^2+y^2).
> 
> 
> Bob Hanlon
> 




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