In this thesis we consider the interpolation of bivariate functions defined over a triangular domain. Barycentric coordinates are used instead of Cartesian coordinates to compute the interpolation points in the triangle. Additionally, Bernstein basis polynomials with some of their key properties are defined and proven to be the basis of the space of polynomials of two variables of total degree at most $n$. We also introduce the Bernstein-Bézier form for polynomials, show that such a form is stable in the infinite norm and define de Casteljau's algorithm for computing values of a polynomial in such a form. Furthermore, formulas for computing Bézier ordinates for the interpolation of continuous functions with Hermite polynomials of degree $n = 3$ and $n=5$, which we call Argyris elements, are derived. Both cases are illustrated with practical examples to make it easier to understand. We also consider interpolation over two adjacent triangles, and we derive and prove the conditions which ensure $C^1$ smoothness between two adjacent triangular patches.
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