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A general integral question

  1. Jan 16, 2005 #1
    Ok...now how do I know if a certain integral is solv/integrat-able or not???
    Just by looking at the inside function, how can I tell if the integral can be solved or not??
     
  2. jcsd
  3. Jan 17, 2005 #2

    dextercioby

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    How about these steps:

    1.Try conventional methods:part integration,substitutions,partial fraction decompositions,residues theorem.

    2.If it doesn't work,then search for it in "Gradsteyn & Rythzik".

    3.If it's not there,the primitive/anitderivative exists,but it's not expressible through elementary functions.

    Daniel.
     
  4. Jan 17, 2005 #3
    The Wolfram Integrator can also be helpful as a quick reference technique.
     
  5. Jan 17, 2005 #4

    dextercioby

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    Trust me,that one is useless for nasty integrals.I tried it for about 3 times over the last month and it wouldn't give me anything... :grumpy:


    Daniel.
     
  6. Jan 17, 2005 #5

    Zurtex

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    Really? Can you give me an example please.
     
  7. Jan 17, 2005 #6

    dextercioby

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    I tried an integral that comes up in the Laplace Transform of arctangent

    [tex] \int_{0}^{+\infty} e^{-sx}\arctan x dx [/tex]

    Of course,i asked for the antidifferential,i thought i could apply the theorem of Leibniz & Newton myself...

    Daniel.
     
  8. Jan 17, 2005 #7

    Zurtex

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    Works fine for me when I enter:

    Code (Text):
    Exp[-s x] ArcTan[x]
     
  9. Jan 17, 2005 #8

    dextercioby

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    Thenx,Zurtex,there's no wonder i couldn't do it... :tongue2: I misstyped something... :grumpy:
    I like the result,though... :tongue2:

    Daniel.
     
  10. Jan 17, 2005 #9

    Zurtex

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    Yeah I can't help thinking Wolfram are trying to introduce their own brand of maths :wink:
     
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