Il giorno mer, 23/12/2009 alle 22.14 -0500, David Winsemius ha scritto: > > for(i in 1:n){ > > submat <- data[1:i,] > > C <- colSums(submat) > > } > > > In R the loop is not necessary, even confusing as you are demonstrating: > > > mat <- matrix(rnorm(100), nrow=10) # 10 x 10 > > colSums(mat[1:5, ]) # sums of 1st 5 rows > [1] 3.33331735 0.86672248 -3.10971483 1.23620455 -0.31887421 > -0.50544837 > [7] 3.13636155 0.02175862 -2.18816961 -1.31760196
It would be unnecessary also in Matlab. In the real code I need to store the partial sums (the example overwrites them, so it looks like wasted loops). Francesco. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.