st: vec of upper triangle

[Edwin Leuven <e.leuven@uva.nl>]

hello,

i was wondering whether anyone is aware of a good (fast) way of putting 
the upper triangle of a square matrix into a vector?

example:

1 2 3
2 4 5
3 5 6

into:

1
2
4
3
5
6

or

1
4
6
2
5
3

or

1
2
3
4
5
6

?

thanks!

edwin

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/