Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.

# st: RE: RE: A math question

 From CJ Lan To "statalist@hsphsun2.harvard.edu" Subject st: RE: RE: A math question Date Fri, 21 Dec 2012 15:42:03 +0000

```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.

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Feiveson, Alan H. (JSC-SK311)
Sent: Friday, December 21, 2012 10:28 AM
To: statalist@hsphsun2.harvard.edu
Subject: st: RE: A math question

CJ -The median is one number, not a function - so it doesn't make sense to talk about differentiating it.

If you mean what is the derivative of abs(x^3) with respect to x, it would be 3*x^2, because the derivative for x < 0 is the same as for x > 0 = 3*x^2.

Al Feiveson

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of CJ Lan
Sent: Friday, December 21, 2012 9:13 AM
To: statalist@hsphsun2.harvard.edu
Subject: st: A math question

Folks,

I am not sure if this is an appropriate question but I am hoping someone wh= o knows the answer do not mind rendering her/his hands.

What is the derivative of the median(abs(x^3)) with respect to x ?

Thank you.

CJ

This message has been scanned for malware by Websense. www.websense.com

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/faqs/resources/statalist-faq/
*   http://www.ats.ucla.edu/stat/stata/

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/faqs/resources/statalist-faq/
*   http://www.ats.ucla.edu/stat/stata/

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/faqs/resources/statalist-faq/
*   http://www.ats.ucla.edu/stat/stata/
```