[R] Computing time for matrix addition or subtraction

[Gabor Grothendieck]

This is slightly faster but not by much:

ad <- function(m, a) { diag(m) <- diag(m) + a; m }
R <- ad(P %*% P - t(P) - P, 1)


On 11/12/06, YONGWAN CHUN <chun.49 at osu.edu> wrote:
> Hello,
>
>
> I wonder by chance if there is a way to reduce computing time for matrix addition or subtraction. With a lot of iterations, it would be helpful to reduce a little amount time.
>
> Simple example is as below
>
> n <- 2000
> P <- matrix(rnorm(n*n),n,n)
> PP <- P %*% P
> M <- diag(n) - P
> R <- M + t(M) - diag(n) +  PP
>
> I would like to reduce time in calculating R.
>
> Thanks,
>
> Yongwan
>
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