# Re: st: Basic matrix functions

 From Tirthankar Chakravarty <[email protected]> To [email protected] Subject Re: st: Basic matrix functions Date Wed, 27 Jan 2010 19:44:53 +0530

```<>

There are probably many ways to do this, but here is one:

*****************************
clear*
set matsize 1000
mat define example = matuniform(1000,14)

// extract the 77th row (say)
mat define example2 = example[77, 1...]
mat list example2

// append in a loop
forv i=1/100 {
mat define example3 = (nullmat(example3) \ matuniform(1,14))
}
mat list example3

// calculate the standard deviation of each column (using Mata)
mata: st_matrix("example4", diagonal(sqrt(variance(st_matrix("example3")))))
mat list example4
*****************************

On Wed, Jan 27, 2010 at 7:21 PM, XU Moqi <[email protected]> wrote:
> Dear list,
>
> I'm struggling to use the matrix functions:
>
> 1) I have a nx14 matrix called A and would like to extract a new matrix
> that consists of line i of Matrix A.
>
> 2) I'm running a loop, and in each stage, I create a new 1x14 matrix. I
> would like to append this line to a matrix B.
>
> 3) Then I would like to calculate the standard deviation of each column
> of matrix B.
>
> Thank you very much for your help!
>
> Moqi
>
>
>
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/
>

--
To every ω-consistent recursive class κ of formulae there correspond
recursive class signs r, such that neither v Gen r nor Neg(v Gen r)
belongs to Flg(κ) (where v is the free variable of r).

*
*   For searches and help try:
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```