> (a <- matrix(1:6 , nrow = 2, byrow = T)) [,1] [,2] [,3] [1,] 1 2 3 [2,] 4 5 6 # 1行目を2倍、2行目を3倍する > diag(2:3) %*% a [,1] [,2] [,3] [1,] 2 4 6 [2,] 12 15 18 # 1列目を2倍、2列目を3倍、3列目を4倍する > a %*% diag(2:4) [,1] [,2] [,3] [1,] 2 6 12 [2,] 8 15 24 # sweep関数を使った方法 > sweep(a, 1, 2:3, FUN = "*") [,1] [,2] [,3] [1,] 2 4 6 [2,] 12 15 18 > sweep(a, 2