There are a few (nasty?) side-effects to c(), one of which is stripping a matrix of its dimensionality. E.g.,
x <- matrix(1:4, 2) c(x) [1] 1 2 3 4 So that's probably what happened to you. R has a somewhat odd feature of not really considering a pure vector as a column or row vector but being willing to change it to either: e.g. y <- 1:2 x %*% y y %*% x y %*% y while matrix(y) %*% x throws an error, which can also trip folks up. You might also note that x * y and y*x return the same thing in this problem. Getting back to your problem: what are v and b and what are you hoping to get done? Specifically, what happened when you tried v*b (give the exact error message). It seems likely that they are non-conformable matrices, but here non-conformable for element-wise multiplication doesn't mean the same thing as it does for matrix multiplication. E.g., x <- matrix(1:4,2) y <- matrix(1:6,2) dim(x) [1] 2 2 dim(y) [1] 2 3 x * y -- here R seems to want matrices with identical dimensions, but i can't promise that. x %*% y does work. Hope this helps and yes I know it can seem crazy at first, but there really is reason behind it at the end of the tunnel, Michael On Sun, Nov 6, 2011 at 12:11 AM, Steven Yen <s...@utk.edu> wrote: > My earlier attempt > > dp <- v*b > > did not work. Then, > > dp <- c(v)*b > > worked. > > Confused, > > Steven > > At 09:10 PM 11/4/2011, you wrote: > > Did you even try? > > a <- 1:3 > x <- matrix(c(1,2,3,2,4,6,3,6,9),3) > a*x > > [,1] [,2] [,3] > [1,] 1 2 3 > [2,] 4 8 12 > [3,] 9 18 27 > > Michael > > On Fri, Nov 4, 2011 at 7:26 PM, Steven Yen <s...@utk.edu> wrote: >> is there a way to do element-by-element multiplication as in Gauss >> and MATLAB, as shown below? Thanks. >> >> --- >> a >> >> 1.0000000 >> 2.0000000 >> 3.0000000 >> x >> >> 1.0000000 2.0000000 3.0000000 >> 2.0000000 4.0000000 6.0000000 >> 3.0000000 6.0000000 9.0000000 >> a.*x >> >> 1.0000000 2.0000000 3.0000000 >> 4.0000000 8.0000000 12.000000 >> 9.0000000 18.000000 27.000000 >> >> >> -- >> Steven T. Yen, Professor of Agricultural Economics >> The University of Tennessee >> http://web.utk.edu/~syen/ >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> 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. >> > > -- > Steven T. Yen, Professor of Agricultural Economics > The University of Tennessee > http://web.utk.edu/~syen/ ______________________________________________ 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.
