st: Append new row to existing matrix

["Sandy Y. Zhu" <sandy.zhu@yale.edu>]

Hi guys:

How can I append a new row to an existing matrix? Basically, I'm
trying to update the matrix in a loop,

I have:

for i=1 to 900
{reg y x1 x2 x3
mat beta=e(b)

append e(b) to an existing matrix}

Basically, I  have 900 regressions to run, and I  need to save the
beta values from each regression. I would like to save them all in a
matrix, so the first row in the matrix saves the betas from the 1st
regression, the 2nd row would save the coefficients from the 2nd
regression, etc....


Thank you!

--
Yours sincerely,

Sandy Y. Zhu
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