st: Mata programming questions; STATA 12 (referencing to columns using stringnames)

["J. J. W." <bsc.j.j.w@gmail.com>]

Dear all,

I have a few questions regarding Mata programming in Stata 12. The
questions are as follows:

- Is it possible to create a matrix that automatically increases in
size? (i.e. suppose I define a matrix of size 5 x 5, but after a while
I want a larger matrix, can I increase the size of my current matrix
without defining a new one or redefining the old one? Can I "just add"
something?)

- How should I update a value inside a matrix? Suppose the following code:
matrix define test = J(2,2,.)
matrix define test[1,1] = 5

This is how I update my matrix, but is this also the "correct" way to do this?

- Last, I would like to ask how the regress function can create
_beta["varname"] to refer to the coefficients. I would like that too!
How can I create that?

Thanks in advance!

Yours sincerely,

Wen Jun Jie
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