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st: RE: return the maximum and its corresponding value of a matrix in Mata


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: return the maximum and its corresponding value of a matrix in Mata
Date   Sun, 5 Nov 2006 19:17:59 -0000

If you sort on the first column, the value
in the second column corresponding to the 
maximum of the first will end up last too, and as 
such accessible. 

: x = (3,2\5,3\4,6)

: sortx = sort(x,1)

: sortx
       1   2
    +---------+
  1 |  3   2  |
  2 |  4   6  |
  3 |  5   3  |
    +---------+

: sortx[rows(x),2]
  3

Nick 
n.j.cox@durham.ac.uk 

Le Wang
 
> I have a question regarding Mata. Suppose I have an imaginary matrix
> with two columns as follows,
> x                      y
> 2.9479707       .15
> 2.926226         .16
> 2.8994321       .17
> 2.8691981       .18
> 2.8368784       .19
> 2.8035694        .2
> 2.7701303       .21
> 2.7372142       .22
> 2.705299         .23
> 2.6747184        .24
> 
> I want Mata to return the maximum values of column 1 (x) AND its
> corresonding values in column 2 (y), in this example, 2.9479707 and
> 0.15. I understand I can use -rowmax- to find the maximum, but I am
> not quite sure how to find the corresponding value.

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