Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Ln x dx

  1. Jan 4, 2004 #1
    Integrat Ln[x]dx!!!!
  2. jcsd
  3. Jan 4, 2004 #2
    Consider it as 1*ln(x) and use parts.
  4. Jan 4, 2004 #3
    If you don't feel like doing it, you can always use:

    The Integrator

    It gives the answer:

    -x + x \ln x
  5. Jan 5, 2004 #4
    Is [x] greatest integer function??
  6. Jan 5, 2004 #5
    Hmm, didn't consider that. I'm not sure there'd be a closed form expression for [itex]\int ln[x] dx [/itex]
    where [itex][x][/itex] is the next greatest integer function. It'd be easy enough to get a numerical answer if the interval was specified though.
    Last edited: Jan 5, 2004
  7. Jan 5, 2004 #6
    You could break the integral into a summation. [x] is constant between intervals of integers, so you end up with a sum of trivial integrals.

    I think this is what Lonewolf is proposing (please excuse my ignorance!)

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook