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Re: Peculiar output from DSolve

  • To: mathgroup at
  • Subject: [mg37015] Re: [mg36994] Peculiar output from DSolve
  • From: Selwyn Hollis <selwynh at>
  • Date: Sun, 6 Oct 2002 05:33:16 -0400 (EDT)
  • References: <>
  • Sender: owner-wri-mathgroup at

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 


BobHanlon at wrote:
> In a message dated 10/4/2002 5:13:02 AM, selwynh at 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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