On Fri, 7 Oct 2005, Prof Brian Ripley wrote: > If A is the matrix the answer is 2*(1 - 2^(-A)), which took about 10secs > for an example of your size. > >> From \sum_{i=1}^n x^{1-i} = (1-x^{-n})/(1-x), E & OE.
NB: I have assumed n >= 1 here, as people nornally do when using 1:count. > On Fri, 7 Oct 2005, Tim Smith wrote: > >> I have a 7000x7000 matrix, and each element is an integer. For each >> element, I want to apply the function : >> >> wt <- 0 >> for(q in 1:count){ >> wt <- wt + 0.5^(q-1) >> } >> >> I get the value of 'count' from the elements in the matrix , and want to >> store the corresponding 'wt' value for that element. >> >> I suppose I could loop through the matrix, and apply the function to >> each element but this would take a really really long time. Are there >> any quicker ways to get the same result? > > -- > Brian D. Ripley, [EMAIL PROTECTED] > Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ > University of Oxford, Tel: +44 1865 272861 (self) > 1 South Parks Road, +44 1865 272866 (PA) > Oxford OX1 3TG, UK Fax: +44 1865 272595 > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html