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Ln x dx

 
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Jan4-04, 05:41 PM   #1
 
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Ln x dx


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

The Integrator

It gives the answer:

[tex]
-x + x \ln x
[/tex]
 
Jan5-04, 04:22 AM   #4
 

Ln x dx


Is [x] greatest integer function??
 
Jan5-04, 09:19 AM   #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.
 
Jan5-04, 10:24 AM   #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!)

Regards,
Sam
 
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