2. The Euclidean norm (2-norm) of an real N-dimensional vector x is its length (the distance
from the origin to the point x in N-dimensional hyperspace **R**<sup>N</sup>). It is calculated as
N
||x|| =
√∑ x²(n), <x, y > = ∑ x(n) y(n)
n=1
n=1
(a) Rewrite < x, y > in terms of matrix-vector operations.
(b) Define ||x|| in terms of the inner product <...>.
(c) Simplify <ax, y >, where a is a scalar constant.
(d) Using the inner product <...>, rewrite the MSE expression
1 N<sub>v</sub> M
E =
N<sub>v</sub> ∑ ∑ [t<sub>p</sub>(i) - y<sub>p</sub>(i)]<sup>2</sup>
p=1 i=1
twice, once using t(i) and y(i) which have dimensions N<sub>v</sub> by 1 and again using t<sub>p</sub> and y<sub>p</sub>
which have dimensions M by 1.