How can i know through MATLAB tool that given function is convex or not?

22 次查看（过去 30 天）
zahid
zahid 2016-5-10
评论： zahid 2016-5-11
Dear ALL, is there any way to find the function is convex or not in MATLAB?As an example i am giving you the following two functions in order to check which one is convex.
These are well known functions used in robust estimation.How can i show through matlab tool the function is convex or not?
Thanks

请先登录，再回答此问题。

采纳的回答

Walter Roberson
Walter Roberson 2016-5-10
Look at the number of zeros of derivatives and the signs of derivatives. Repeat with derivatives of that, as many times as necessary to figure out the rule.
  6 个评论
显示 4更早的评论

请先登录，再进行评论。

更多回答（1 个）

Roger Stafford
Roger Stafford 2016-5-10
编辑：Roger Stafford 2016-5-10
If your function has a second derivative, it is convex if and only if that second derivative is always non-negative. If the second derivative is unobtainable, a function is convex if any chord connecting two points on the curve always lies on or above the portion of the curve between the two points. Look at this site for a definition:
https://en.wikipedia.org/wiki/Convex_function
Your f2 function is certainly not convex as can be determined by just looking at it. A simple plot reveals that f1 is convex over the interval where it is real-valued.

类别

在 Help Center 和 File Exchange 中查找有关 Calculus 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by