The construction of a planar convex hull is an essential operation in computational geometry. It has been proven that the time complexity of an exact solution is Ω(NlogN). In this paper, we describe an algorithm with time complexity O(N + k), where k is parameter controlling the approximation quality. This is beneficial for applications processing a large number of points without necessity of a...

Given points in convex position in three dimensions, we want to find an approximating convex surface consisting of spherical patches, such that all points are within some specified tolerance bound ε of the approximating surface. We describe a greedy algorithm which constructs an approximating surface whose spherical patches are associated to the faces of an inscribed polytope formed from a subs...

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We prove a direct theorem for convex polynomial L p-approximation, 0 < p < 1, in terms of the classical modulus of smoothness ! 3 (f; t) p. This theorem may be regarded as an extension to L p of the well-known pointwise estimates of the Timan type and their variants of R. DeVore, Y. K. Hu and D. Leviatan for convex approximation in L p. It leads to a characterization of convex functions in Lips...