So, trying to convert a very long, somewhat technical bit of lin alg MATLAB code to R. Most of it working, but raninto a stumbling block that is probaably simple enough for someone to explain.
Basically, trying to 'line up' MATLAB results from an element-wise division of a matrix by a vector with R output. Here is a simplified version of the MATLAB code I'm translating: NN = [1, 2, 3; 4, 5, 6]; % Example matrix lambda = [2, 3, 4]; % Example vector result_matlab = NN ./ lambda; which yields 0.50000 0.66667 0.75000 2.00000 1.66667 1.50000 So, the only way I have stumbled onto in R to generate the same results is to use 'sweep'. The following 'works', but I'm hoping someone can explain why I need something as convoluted as this seems (to me, at least). NN <- matrix(c(1, 2, 3, 4, 5, 6), nrow = 2, byrow = TRUE) # Example matrix lambda <- c(2, 3, 4) # Example vector sweep(NN, 2, lambda, "/") [,1] [,2] [,3] [1,] 0.5 0.6666667 0.75 [2,] 2.0 1.6666667 1.50 First tried the more 'obvious' NN/lambda, but that yields 'the wrong answer' (based solely on what I'm trying to accomplish): [,1] [,2] [,3] [1,] 0.500000 0.5 1.0 [2,] 1.333333 2.5 1.5 So, why 'sweep'? [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.