Comments on: Log concave functions http://www.johndcook.com/blog/2009/01/09/log-concave-functions/ The blog of John D. Cook Fri, 19 Mar 2010 19:25:59 -0400 http://wordpress.org/?v=2.8.4 hourly 1 By: KW http://www.johndcook.com/blog/2009/01/09/log-concave-functions/comment-page-1/#comment-25234 KW Mon, 28 Sep 2009 13:46:03 +0000 http://www.johndcook.com/blog/?p=1234#comment-25234 John, A concave function could be increasing or decreasing fast in one segment of the curve and slow in other segments, while the upper half of a circle seems increasing and decreasing constantly. My question is how to interpret this in a mathematics form. Thanks. KW John,

A concave function could be increasing or decreasing fast in one segment of the curve and slow in other segments, while the upper half of a circle seems increasing and decreasing constantly. My question is how to interpret this in a mathematics form.

Thanks.

KW

]]> By: John http://www.johndcook.com/blog/2009/01/09/log-concave-functions/comment-page-1/#comment-21290 John Fri, 17 Jul 2009 00:30:42 +0000 http://www.johndcook.com/blog/?p=1234#comment-21290 seh chun: For a reference, see the book by Stephen Boyd mentioned at the bottom on the post. seh chun: For a reference, see the book by Stephen Boyd mentioned at the bottom on the post.

]]> By: seh chun http://www.johndcook.com/blog/2009/01/09/log-concave-functions/comment-page-1/#comment-21289 seh chun Fri, 17 Jul 2009 00:23:39 +0000 http://www.johndcook.com/blog/?p=1234#comment-21289 Hi, This post is great and useful. About a point you have put, saying "The running average of a log concave function is also log concave". May I know is there any book / reference that I can find more information about that? Thanks. Hi,

This post is great and useful. About a point you have put, saying “The running average of a log concave function is also log concave”. May I know is there any book / reference that I can find more information about that?

Thanks.

]]> By: John http://www.johndcook.com/blog/2009/01/09/log-concave-functions/comment-page-1/#comment-13431 John Mon, 16 Feb 2009 21:43:08 +0000 http://www.johndcook.com/blog/?p=1234#comment-13431 Thanks! You were right: "logic" was a typo for "logit." I've corrected the post. Thanks! You were right: “logic” was a typo for “logit.” I’ve corrected the post.

]]> By: gb http://www.johndcook.com/blog/2009/01/09/log-concave-functions/comment-page-1/#comment-13430 gb Mon, 16 Feb 2009 21:25:27 +0000 http://www.johndcook.com/blog/?p=1234#comment-13430 Great post. One minor issue - I haven't seen the function exp(x)/(1+exp(x)) called the inverse logic function before (which might simply be ignorance on my part). (I have seen it called the <a href="http://en.wikipedia.org/wiki/Logit" rel="nofollow">inverse logit function</a> or the <a href="http://en.wikipedia.org/wiki/Logistic_function" rel="nofollow">logistic function</a>. ) However, given "logit" and "logic" only differ by one character, I did wonder if it might have been a simple typo. Great post.

One minor issue – I haven’t seen the function exp(x)/(1+exp(x)) called the inverse logic function before (which might simply be ignorance on my part).

(I have seen it called the inverse logit function or the logistic function. )

However, given “logit” and “logic” only differ by one character, I did wonder if it might have been a simple typo.

]]> By: Welcome to Carnival of Mathematics 48 = 6!!! « Concrete Nonsense http://www.johndcook.com/blog/2009/01/09/log-concave-functions/comment-page-1/#comment-12585 Welcome to Carnival of Mathematics 48 = 6!!! « Concrete Nonsense Fri, 30 Jan 2009 18:57:28 +0000 http://www.johndcook.com/blog/?p=1234#comment-12585 [...] models the distribution of time customers spend in coffee shops and also gives some properties of log-concave functions (I did not know before that they are closed under [...] [...] models the distribution of time customers spend in coffee shops and also gives some properties of log-concave functions (I did not know before that they are closed under [...]

]]>