Let V be a vector space. An inner product on V is a rule that assigns to each pair v, w ∈ V a real number hv, wi such that, for all u, v, w ∈ V and α ∈ R, hαv, wi = αhv, wi. hu, v + wi = hu, vi hv, αwi = αhv, wi. An inner product space is a vector space with an inner product. Each of the vector spaces Rn, Mm×n, Pn, and FI is an inner product space: