“…Shen, G.-Z. Wang and Y.-W. Wei in recent papers [9,10] and [11], respectively. These special cases of triangular patches were obtained by certain constrained trivariate extensions of univariate normalized B-bases of the first and second order trigonometric and of the fourth order algebraic trigonometric vector spaces F α 2 = span {1, cos (t) , sin (t) : t ∈ [0, α]} , F α 4 = span {1, cos (t) , sin (t) , cos (2t) , sin (2t) : t ∈ [0, α]} and M α 4 = span {1, t, cos (t) , sin (t) : t ∈ [0, α]} , respectively, where α ∈ (0, π) is an arbitrarily fixed shape (or design) parameter.…”