Outerm

Purpose

Computes the outer product of any number of vectors with multiple factors.

Synopsis

mwa = outerm(facts,lo,vect)

Description

The input to outer is a 1 by N cell array facts, where each cell contains a matrix of factors for one of the modes (a.k.a. ways, dimensions, or orders), with each factor being a column in the matrix.

Optional inputs are lo the number of a mode to leave out in the formation of the outer product, and a flag vect which causes the function to not sum and reshape the final factors when set to 1. (This option is used in the alternating least squares steps in PARAFAC.)

The output is the multiway array resulting from multiplying the factors together mwa, or the strung out individual factors.

Examples:

a = [[1:7]' [2 4 1 3 5 7 6]'];  % 7x2

b = [sin([1:.5:5]') cos([1:.5:5]')];  % 9x2

c = [[1:8 0 0]', [0 0 1:8]'];  % 10x2

x = outerm({a,b,c});  % 7x9x10

See Also

gram, mpca, parafac, tld