DW1

(A <- matrix(c(2,-1,2,5,3,-2),nrow=3,ncol=2))

##      [,1] [,2]
## [1,]    2    5
## [2,]   -1    3
## [3,]    2   -2

(B <- matrix(c(1,2,5,0,-3,2,4,-3),nrow=2,ncol=4))

##      [,1] [,2] [,3] [,4]
## [1,]    1    5   -3    4
## [2,]    2    0    2   -3

(AB<-A%*%B)

##      [,1] [,2] [,3] [,4]
## [1,]   12   10    4   -7
## [2,]    5   -5    9  -13
## [3,]   -2   10  -10   14