Multiplies two random matrices, if they are conformable. If one argument is a vector, it will be coerced to either a row or column matrix to make the two arguments conformable. If both are vectors it will return the inner product.
`%*%.rv`(x, y)
x %**% ynumeric or complex matrices or vectors.
The (distribution of the) matrix product. Use drop to
get rid of dimensions which have only one level.
Optimized internally for the case of random matrix multiplied by a constant column vector.
Kerman, J. and Gelman, A. (2007). Manipulating and Summarizing Posterior Simulations Using Random Variable Objects. Statistics and Computing 17:3, 235-244.
See also vignette("rv").
x <- 1:4
(z <- x %*% x) # scalar ("inner") product (1 x 1 matrix)
#> [,1]
#> [1,] 30
drop(z) # as scalar
#> [1] 30
y <- diag(x)
z <- matrix(1:12, ncol = 3, nrow = 4)
y %*% z
#> [,1] [,2] [,3]
#> [1,] 1 5 9
#> [2,] 4 12 20
#> [3,] 9 21 33
#> [4,] 16 32 48
y %*% x
#> [,1]
#> [1,] 1
#> [2,] 4
#> [3,] 9
#> [4,] 16
x %*% z
#> [,1] [,2] [,3]
#> [1,] 30 70 110