matmult {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

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