τn⁡(z)=|ϕ⁡(z)ϕ′⁡(z)⋯ϕ(n-1)⁡(z)ϕ′⁡(z)ϕ′′⁡(z)⋯ϕ(n)⁡(z)⋮⋮⋱⋮ϕ(n-1)⁡(z)ϕ(n)⁡(z)⋯ϕ(2⁢n-2)⁡(z)|,