Yes - of course - the derivative should be 3*x*|x|. Thanks for noticing this!
Al
-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of David Hoaglin
Sent: Friday, December 21, 2012 9:53 AM
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: RE: RE: A math question
The median is a function of a distribution. You did not specify the distribution of x. If you explained the context for your question, we might be able to shed better light.
David Hoaglin
On Fri, Dec 21, 2012 at 10:42 AM, CJ Lan <CJ@jupiter.fl.us> wrote:
> Al,
>
> I think the "median" is a function, just like the "mean" is a function, not just a number.
>
> BTW, the derivative of abs(x^3) should be 3*x*abs(x) because the
> derivative can be derived as
> abs(x^3)/(x^3)*(3*x^2) = 3*abs(x)*x^2/x = 3*x*abs(x).
>
> I wish others could shed a light too? Thx.
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