st: matrix size and ranking values

["NEYMOTIN, FLORENCE" <neymotin@calmail.berkeley.edu>]

Hi, before you complain that this is not stata-`ese' let me start by saying that this is really 
coded in matlab but needs to be forced into stata, hence my difficulties.

 If I have 1000 vectors (nx1 matrices) and I would like to compare the first value in each vector 
in order to find the 50th largest, and the 950th largest of these values, is there an easy way to 
do this in stata?  I know I can't have more than 800 entries in any one vector, so I'm not able to 
simply create a vector that contains within it the first value in each of the original 1000 
vectors.  I am also NOT able to change the data because it is already in a mode that needs to be 
put into restore later.  Is there an easy algorithm anyone can think of to do this?
Thank you,
Florence
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