►A function is convex on if
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►If is twice differentiable, then is convex iff on .
A continuously differentiable function is convex iff the curve does not lie below its tangent at any point.
►►►Figure 1.4.2: Convex function .
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A. Michaeli (1996)Asymptotic analysis of edge-excited currents on a convex face of a perfectly conducting wedge under overlapping penumbra region conditions.
IEEE Trans. Antennas and Propagation44 (1), pp. 97–101.