Editing Convex function (section)

==Alternative naming==
The term ''convex'' is often referred to as ''convex down'' or ''concave upward'', and the term [[Concave function |concave]] is often referred as ''concave down'' or ''convex upward''.<ref>{{Cite book|last=Stewart|first=James|title=Calculus|publisher=Cengage Learning|year=2015|isbn=978-1305266643|edition=8th|pages=223–224}}</ref><ref>{{cite book|last1=W. Hamming|first1=Richard|url=https://books.google.com/books?id=WLIbeA1aWvUC|title=Methods of Mathematics Applied to Calculus, Probability, and Statistics|publisher=Courier Corporation|year=2012|isbn=978-0-486-13887-9|edition=illustrated|page=227}} [https://books.google.com/books?id=WLIbeA1aWvUC&pg=PA227 Extract of page 227]</ref><ref>{{cite book|last1=Uvarov|first1=Vasiliĭ Borisovich|url=https://books.google.com/books?id=GzQnAQAAIAAJ|title=Mathematical Analysis|publisher=Mir Publishers|year=1988|isbn=978-5-03-000500-3|edition=|page=126-127}}</ref> If the term "convex" is used without an "up" or "down" keyword,  then it refers strictly to a cup shaped graph <math>\cup</math>.  As an example, [[Jensen's inequality]] refers to an inequality involving a convex or convex-(down), function.<ref>{{cite book |title=The Probability Companion for Engineering and Computer Science |edition=illustrated |first1=Adam |last1=Prügel-Bennett |publisher=Cambridge University Press |year=2020 |isbn=978-1-108-48053-6 |page=160 |url=https://books.google.com/books?id=coHCDwAAQBAJ}} [https://books.google.com/books?id=coHCDwAAQBAJ&pg=PA160 Extract of page 160]</ref>