How low is "very low"? This is probably answered by FAQ 7.31 On Thu, Sep 11, 2008 at 9:49 AM, Markus Schmidberger <[EMAIL PROTECTED]> wrote: > Hi, > > I found different results calculating the rowMeans by the function > rowMeans() and a simple for-loop. The differences are very low. But after > this calculation I will start some optimization algorithms (BFGS or CG) and > there I get huge differences (from the small changes in the beginning or > start values, I changed nothing else in the code). > How I can avoid these differences between sum-loops and sum-functions? > > Attached a small testcode using data form Bioconductor. > > Best > Markus > > > library(affy) > data(affybatch.example) > mat <- exprs(affybatch.example)[1:100,1:3] > mat <- exp(1)*mat > mat <- asinh(mat) > > rowM1<- rowMeans(mat) > > t=rep(0,100) # Vektor mit 0en > for(i in 1:100){ > for(j in 1:3) > t[i] <- t[i] + mat[i,j] > } > rowM2 <- t/3 > > m1 <- mat - rowM1 > m2 <- mat -rowM2 > > print(m1-m2) > > sessionInfo() > R version 2.7.1 (2008-06-23) > i386-pc-mingw32 > > locale: > LC_COLLATE=German_Germany.1252;LC_CTYPE=German_Germany.1252;LC_MONETARY=German_Germany.1252;LC_NUMERIC=C;LC_TIME=German_Germany.1252 > > attached base packages: > [1] tools stats graphics grDevices utils datasets methods [8] > base > other attached packages: > [1] affy_1.18.2 preprocessCore_1.2.0 affyio_1.8.0 [4] > Biobase_2.0.1 > -- > Dipl.-Tech. Math. Markus Schmidberger > > Ludwig-Maximilians-Universität München > IBE - Institut für medizinische Informationsverarbeitung, > Biometrie und Epidemiologie > Marchioninistr. 15, D-81377 Muenchen > URL: http://ibe.web.med.uni-muenchen.de Mail: Markus.Schmidberger [at] > ibe.med.uni-muenchen.de > Tel: +49 (089) 7095 - 4599 > > ______________________________________________ > 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. >
-- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve? ______________________________________________ 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.