Difficult integral...


by eljose79
Tags: difficult, integral
eljose79
eljose79 is offline
#1
Aug4-04, 10:03 AM
P: 215
I have problems calculating the integral (here 8 means infinite)

Int(c-i8,c+i8)dsexp(sx)/sR(s) where R(sd) is Riemann,s function i make the change of variable s=c+iu so the new limits are

Int(-8,8)iduexp(cx)exp(iu)/(c+iu)R(c+iu) now what numerical method could i use to calculate it?..thanks.
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Feynman
Feynman is offline
#2
Aug4-04, 10:14 AM
P: 160
what is the analitic expression of R?
eljose79
eljose79 is offline
#3
Aug5-04, 04:59 AM
P: 215
R(s) is Riemann,s zeta function R(s)=1+2^s+3^s+4^s+.............

hope no Feynmann you could give me a hand.

matt grime
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#4
Aug5-04, 05:29 AM
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P: 9,398

Difficult integral...


if only you knew where all the poles were. and if you took a couple of minutes to learn some basic latex your posts would be easier to read. try the thread in general physics
eljose79
eljose79 is offline
#5
Aug6-04, 04:33 AM
P: 215
Latex is hard for me to understand,there are lots opf instruction in fact in the integral...we could do..

Int(-8,8)duexp(iux)/R(c+iu) instead of putting 8 (8=infinite) put N with N big (for example N=10^200000000000) make the change of variable u=Nt then the integral becomes:

Int(-1,1)Ndtexp(iNtx)/R(c+iNt) now the integral (-1,1) can be computed approximately using Gaussian integration.

Yes you could solve it knowing where the poles are but for the function 1/R(s) there are infinite poles so we substitute the problme of calculating an integral to the problem of calculating an infinite series wich is not much better.


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