R sparse matrix power -

i'm using matrix package create large (~14000x14000) sparse matrix lot of zeros. know best way calculate power of matrix?

i tried a_pow2 = a%^%2 error: error in %^% 2 : not matrix. here's simple example returns same error:

a = matrix(3,2,2) = matrix(a,sparse=true) apow2 = a%^%2 

(edited @roland's comments)

a custom function might able solve issue. per documentation of ?expm::`%^%`

compute k-th power of matrix. whereas x^k computes element wise powers, x %^% k corresponds k - 1 matrix multiplications, x %*% x %*% ... %*% x.

we can write new infix operator perform multiplication k-1 times. not sure how scale, works in smaller examples.

> library(matrix) > library(expm) > = matrix(3,2,2) > b = matrix(a,sparse=true) >  > # changed lapply rep list > `%^^%` = function(x, k) reduce(`%*%`, rep(list(x), k)) > # per roland loop approach better on memory > `%^^%` = function(x, k) {for (i in 1:(k - 1)) x <- x %*% x; x} >  > as.matrix(b%^^%2)      [,1] [,2] [1,]   18   18 [2,]   18   18 > a%^%2      [,1] [,2] [1,]   18   18 [2,]   18   18