matmult                 package:base                 R Documentation

Matrix Multiplication

Description:

     Multiplies two matrices, if they are conformable. If one argument
     is a vector, it will be coerced to a either a row or column matrix
     to make the two arguments conformable. If both are vectors it will
     return the inner product.

Usage:

     a %*% b

Value:

     The matrix product.  Use `drop' to get rid of dimensions which
     have only one level.

See Also:

     `matrix', `Arithmetic', `diag'.

Examples:

     x <- 1:4
     (z <- x %*% x)    # scalar ("inner") product (1 x 1 matrix)
     drop(z)             # as scalar

     y <- diag(x)
     z <- matrix(1:12, ncol = 3, nrow = 4)
     y %*% z
     y %*% x
     x %*% z

