• We can combine transposition and matrix product operations to define the ‘inner’ and
‘outer’ products of two vectors. Let a and b be column vectors with elements ai,…an and
bi,…bn, or equivalently, matrices each with dimension n × 1.
• The ‘inner product’ of the two vectors is the sum of the cross-products of their
corresponding elements, which is a scalar. We can obtain this result by transposing a and
multiplying a by b: