# evaluate sum of sum

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## evaluate sum of sum

 Hi R-users, Could anybody show me how to write a code to evaluate sum(z[i] + sum(k[j]*(z[i])^(k[j])), i=1 to 4, j=0 to infinity) ? Thank you so much for any help given.               [[alternative HTML version deleted]] ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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## Re: evaluate sum of sum

 On 16/07/2009, at 2:30 PM, Roslina Zakaria wrote: > Hi R-users, > > Could anybody show me how to write a code to evaluate sum(z[i] + sum > (k[j]*(z[i])^(k[j])), i=1 to 4, j=0 to infinity) ? No.  No-one can.  It is conceptually impossible. (a) Computers cannot do infinite sums; they can only do finite ones. (b) Attempting to approximate infinite sums by finite ones that   computers can do is theoretically possible, but fraught with peril.  E.g. try   summing {1/(j+1)} from 0 to infinity that way.  You may, after a long while,   get a finite answer ..... (c) What is k[j] equal to?  You must have an expression for it, elsewise your question makes no sense at all. If the sequence k[j] is sufficiently nice then you may be able to   determine error bounds.  I.e. for a given epsilon, find an M_0 such that the   sum from 0 to M is within epsilon of the sum to infinity for any M >= M_0. The sum from 0 to M is easy to calculate.         cheers,                 Rolf ###################################################################### Attention:\ This e-mail message is privileged and confid...{{dropped:9}} ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.