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Ln x dx

by PrudensOptimus
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PrudensOptimus
#1
Jan4-04, 05:41 PM
P: 640
Integrat Ln[x]dx!!!!
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Lonewolf
#2
Jan4-04, 05:47 PM
P: 333
Consider it as 1*ln(x) and use parts.
Tron3k
#3
Jan4-04, 10:06 PM
P: 45
If you don't feel like doing it, you can always use:

The Integrator

It gives the answer:

[tex]
-x + x \ln x
[/tex]

himanshu121
#4
Jan5-04, 04:22 AM
himanshu121's Avatar
P: 658
Ln x dx

Is [x] greatest integer function??
Lonewolf
#5
Jan5-04, 09:19 AM
P: 333
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.
sam2
#6
Jan5-04, 10:24 AM
P: 22
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!)

Regards,
Sam


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