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Quick (dumb) Notation Question

  1. May 21, 2009 #1


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    I know writing [tex]\frac{\partial^{1}u}{\partial x^{1}}[/tex] is "bad" notation, but can I still write the sum:

    [tex]\sum^{n}_{k=1}\frac{\partial^{k}u}{\partial x^{k}}[/tex]



    PS. Being able to write LaTeX equations is actually awesome.
  2. jcsd
  3. May 22, 2009 #2


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    When you write it explicitly it looks a bit weird, but I see no objection to using it in such a sum.
  4. May 22, 2009 #3


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    OK. I just wanted to make sure. Thanks!
  5. May 22, 2009 #4
    Can I ask what kind of situation you're getting that sum in?
  6. May 22, 2009 #5


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    While uncommon, I don't see anything bad about it.

    When dealing with just the first derivative of some function, it is superfluous, but completely analogical to the case that [itex]x=x^{1}[/itex]
    Neither of these two notations are "bad" in any way.
  7. May 22, 2009 #6


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    I would even accept
    [tex]\sum_{k=0}^n \frac{\partial^k u}{\partial x^k}[/tex]
    with the understanding that
    [tex]\frac{\partial^0 u}{\partial x^0}= u(x)[/tex]
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