Integral of ln (sin x)

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  1. Thusitha's Avatar
    • Junior Member
    • Location: sydney
    • Posts: 26
    Integral of ln (sin x)
    Hi,
    Could some one tell me how to do the following indefinite integral


    integral { ln (sin x) dx }

    I thought I can do this by integration by parts. But it doesn't seem to work.

    Thanks
  2. Mr M's Avatar
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    Re: Integral of ln (sin x)
    I remembered seeing this before somewhere and Google was my friend.

    http://community.boredofstudies.org/...ml#post3316947

    and here:

    http://mathforum.org/library/drmath/view/72243.html

    You may struggle with an indefinite integral!!!
    Last edited by Mr M; 26-09-2009 at 22:07.
  3. SimonM's Avatar
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    Re: Integral of ln (sin x)
    Isn't that the definite integral which is possible?

    http://www.wolframalpha.com/input/?i...+ln%28sin+x%29
  4. D-Day's Avatar
    • Overlord in Training
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    Re: Integral of ln (sin x)
    Yay for complex numbers.
  5. psychobunnay's Avatar
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    Re: Integral of ln (sin x)
    ...umm damn I've completely forgotton all of C4...
  6. refref's Avatar
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    Re: Integral of ln (sin x)
    (Original post by SimonM)
    Isn't that the definite integral which is possible?

    http://www.wolframalpha.com/input/?i...+ln%28sin+x%29
    the 'polylogarithm function'?

    I get dibs on the loganomial function
  7. Mr M's Avatar
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    Re: Integral of ln (sin x)
  8. DFranklin's Avatar
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    • Location: London
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    Re: Integral of ln (sin x)
    Similarly, try \int \ln(1+\tan x)\,dx...
  9. Thusitha's Avatar
    • Junior Member
    • Location: sydney
    • Posts: 26
    Re: Integral of ln (sin x)
    Hi,
    Thanks for every one who responded. I made a mistake. It was the improper integral, that I needed to find.

    Actually the definite integral I needed to find is integral {ln (t*cos t) dt.}

    I think I should be able to do it now with the above help.

    Thanks for the help again.
  10. Thusitha's Avatar
    • Junior Member
    • Location: sydney
    • Posts: 26
    Re: Integral of ln (sin x)
    Thanks for every one for the help. My problem is resolved.
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