pairwise_Schur_product function

Compute Schur products (element-wise) of all pairwise combinations of columns in matrix

Fast computation of all pairwise element-wise column products of a matrix.

pairwise_Schur_product(x, self = FALSE)

Arguments

• x: A matrix with dimensions r*c.
• self: A logical that determines whether a column should also be multiplied by itself.

Returns

A matrix with the same number of rows as x and a number of columns corresponding to c choose 2 (+ c if self is TRUE), where c is the number of columns of x.

Details

Note that the output order of columns corresponds to the order of the columns in x. First column 1 is multiplied with each of the other columns, then column 2 with the remaining columns etc.

Examples

X <- cbind(rep(1, 4), 1:4, 4:1)
pairwise_Schur_product(X)
pairwise_Schur_product(X, self=TRUE)

Author(s)

Claus Ekstrom claus@rprimer.dk