# User:Jarle Pahr/Convexity

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Notes on convexity as applied to optimization:

http://en.wikipedia.org/wiki/Convex_analysis#Convex_functions

http://www.econ.umn.edu/~msolis/Part5-4.pdf

How to determine if a function is convex/concave: http://www.economics.utoronto.ca/osborne/MathTutorial/CVNF.HTM

A function is convex iff its [epigrah] is a convex set.

If f is a multivaried function on a convex open set S, with continous partial derivatives, then:

- f is concave iff H(x) is negative semi-definite for all x in S.
- f is convex iff H(x) is positive semi-definite for all x in S.