Visualization of the \(\varepsilon \)-subdifferential of piecewise linear-quadratic functions. (English) Zbl 1406.90092

Summary: Computing explicitly the \(\varepsilon\)-subdifferential of a proper function amounts to computing the level set of a convex function namely the conjugate minus a linear function. The resulting theoretical algorithm is applied to the the class of (convex univariate) piecewise linear-quadratic functions for which existing numerical libraries allow practical computations. We visualize the results in a primal, dual, and subdifferential views through several numerical examples. We also provide a visualization of the Brøndsted-Rockafellar theorem.


90C25 Convex programming
90C20 Quadratic programming


PLCP; Scilab; SQPlab; CCA
Full Text: DOI arXiv


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