For
k = 3
These six support points are represented as
where θ is the
rotation angle for axes x1
and x2; φ is the rotation angle for axes x1 and x3
; and α is the rotation angle for axes x2 and x3.
The h3(r) is an increasing function for r > 0. Then the maximum of |X’X| is attended when α = 0, θ = 0 and ψ = 0. Hence the original star points are the D-optimal star points.