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Article #66Re: Better than Cauchy-Schwarz
From: Vincent Broman
Date: Thu, 10 Sep 1992 23:25
Date: Thu, 10 Sep 1992 23:25
20 lines
1637 bytes
1637 bytes
let C = 1/8,
let f be L1 and L2 on [0,\infty),
and let \int_0^\infty f(x) x dx < C \int_0^\infty f(x) dx.
Then
\int_0^C f(x) (C-x) dx >= \int_C^\infty f(x) (x-C) dx
implies with a slight amount of work
\int_0^{2 C} f(x) dx >= \int_{2 C}^\infty f(x) dx,
meaning that the median is not more than twice the mean.
Apply Cauchy-Schwartz to f and the characteristic function on [0,2C].
Then,
\int_0^\infty f^2 >= ( \int_0^{2 C} f )^2 / (2 C)
>= ( 1/2 \int_0^\infty f )^2 / (2 C)
= ( \int_0^\infty f )^2.
Vincent Broman, code 572 bayside, = o
Naval Command Control and Ocean Surveillance Center, RDT&E Div. = _ /- _
San Diego, CA 92152-5000, USA = (_)> (_)
Internet Email: broman@nosc.mil Fax: +1 619 553 1635 Phone: +1 619 553 1641
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Newsgroups: sci.math.research Path: arc1-ca.pugleaf.net!sparky!uunet!usc!sdd.hp.com!ux1.cso.uiuc.edu!news.cso.uiuc.edu!usenet From: broman@schroeder.nosc.mil (Vincent Broman) Subject: Re: Better than Cauchy-Schwarz References: <18ltblINN8oq@darkstar.UCSC.EDU> Message-ID: <BROMAN.92Sep10152535@schroeder.nosc.mil> Sender: Daniel Grayson <dan@math.uiuc.edu> Reply-To: broman@nosc.mil X-Submissions-To: sci-math-research@uiuc.edu Organization: Naval Command Control and Ocean Surveillance Center, RDT&E Div. X-Administrivia-To: sci-math-research-request@uiuc.edu Approved: Daniel Grayson <dan@math.uiuc.edu> In-Reply-To: sutin@helios.ucsc.edu's message of Wed, 9 Sep 1992 22:20:37 GMT Date: Thu, 10 Sep 1992 23:25:35 GMT Lines: 22