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can the prime really not solve this integral?
02-27-2014, 02:11 PM
Post: #12
RE: can the prime really not solve this integral?
(02-27-2014 12:21 PM)parisse Wrote:  You get a numeric answer with:
int(x^3/(exp(x)-1),x,0,inf)
then shift-enter.
x^3/(exp(x)-1) does not have an antiderivative than you can express with elementary function (special functions required, polylogs here). There is probably a trick than can give you the exact answer (pi^4/15) for the definite integral, any idea? On a voyage 200, you don't get the exact value by the way.

Possibly a dumb question, but why is the result dependent on the Rad/Deg setting when solving this? If the calc is in Degrees the result (on my calculator) is 372.07.... Other integrals involving exp(x) (for instance int(exp(x^2),x,0,.5)) seems not to be influenced by the Deg/Rad setting. Am I missing something?

Cheers, Terje
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RE: can the prime really not solve this integral? - Terje Vallestad - 02-27-2014 02:11 PM



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