massimodisasha wrote: > hi, > i'm new to R > i have a little script in matlab.... > now i'm porting it to R but i've some problem. > how can i write in R language this > matlab/octave code: > > LX = L ; >>> L is a matrix > ss = size(LX,1); > E_N_2 = zeros(ss,2); > > for i = 1:ss > E_2 = E_0 + LX(i,1)*C(3)+LX(i,2)*C(4); >>>> E_0 , C(3), c(4) > are costant > N_2 = N_0 + LX(i,2)*C(3)-LX(i,1)*C(4); > r=[ E_2,N_2]; > E_N_2(i,:)=r; > end > E_N_2 > > i'm try so : > > library(matlab) > LX <- L > ss <- dim(LX) > ss <- ss[1] > E_N_2 <- zeros(ss,2) > for(i in 1:ss) > ..... > .....? > > thanks for any help :-) > Massimo > > my mayor problem is to know how the "cicle for" works
Perhaps a more important problem is learning how to use matrix algebra. Loops are notoriously slow in R, and worth avoiding in octave as well. E_0 <- 12 N_0 <- 13 C3 <- 21 C4 <- 22 L <- matrix(c(1,2,3,4,5,6,7,8,9),ncol=3) ss <- dim(L)[1] LX <- L[1:ss,1:2] C <- matrix(c(C3,C4,-C4,C3),ncol=2) EN <- matrix(rep(c(E_0,N_0),ss),ncol=2,byrow=TRUE) E_N_2 <- EN + LX %*% C E_N_2 -- --------------------------------------------------------------------------- Jeff Newmiller The ..... ..... Go Live... DCN:<[EMAIL PROTECTED]> Basics: ##.#. ##.#. Live Go... Live: OO#.. Dead: OO#.. Playing Research Engineer (Solar/Batteries O.O#. #.O#. with /Software/Embedded Controllers) .OO#. .OO#. rocks...1k ______________________________________________ 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 and provide commented, minimal, self-contained, reproducible code.