Les matrices (3/3)

• Multiplication de matrices %*%

> X = matrix(data=1:6, nrow=2, nc=3)
> Y = matrix(data=-2:3, nrow=3, nc=2)
> X
     [,1] [,2] [,3]
[1,]    1    3    5
[2,]    2    4    6
> Y
     [,1] [,2]
[1,]   -2    1
[2,]   -1    2
[3,]    0    3
> Y %*% X 
     [,1] [,2] [,3]
[1,]    0   -2   -4
[2,]    3    5    7
[3,]    6   12   18