[R] Matrix addition function

Michael Knudsen micknudsen at gmail.com
Thu Aug 13 15:11:03 CEST 2009

On Thu, Aug 13, 2009 at 11:35 AM, Lina Rusyte<linera27 at yahoo.co.uk> wrote:

Hi Lina,

> What function can I use for matrices addition? I couldn’t find any information about it in the manual or in the internet.
> (A+B suits, when the number of matrixes is small, function sum() doesn’t suit for matrices addition, because it sums all variables in the matrices and produces as an answer single number, not a matrix).

I don't know of any function doing that, but you could easily write a
one yourself. Suppese that X is a list of matrices. Then you could
e.g. do as follows:

matrixSum = function(X)
   N = length(X)
   if (N==2) return(X[[1]]+X[[2]])
   else return(matrixSum(X[[1:(N-1)]],X[[N]]))

I guess that one should do the trick.


Michael Knudsen
micknudsen at gmail.com

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