Mata Answers This Admirably!
. mata :
------------------------------------------------- mata (type end to exit) ------------------
: m = (1,2,3\4,5,6\7,8,9)
: sqrt(m)
1 2 3
+-------------------------------------------+
1 | 1 1.414213562 1.732050808 |
2 | 2 2.236067977 2.449489743 |
3 | 2.645751311 2.828427125 3 |
+-------------------------------------------+
Otherwise, in Stata <9, this is essentially the same question
as one asked a few days ago. An ancient program
to do this, and other _e_lement_w_ise _m_onadic
_f_unction problems, is -matewmf-:
STB-56 dm79 . . . . . . . . . . . . . . . . . . Yet more new matrix commands
(help matcorr, matewmf, matvsort, svmat2 if installed) . . N. J. Cox
7/00 pp.4--8; STB Reprints Vol 10, pp.17--23
commands to produce a correlation matrix, elementwise monadic
function of another matrix, selected subsets of matrix rows
and columns, vec or vech of a matrix, elements sorted within
a vector, matrix from a vector, and commands to save matrices
That name is so unlikely that you would never guess it, but
. search matrix
would have pointed to it.
. matrix A = (1,2,3\4,5,6\7,8,9)
. matewmf A B , function(sqrt)
. mat li B
B[3,3]
c1 c2 c3
r1 1 1.4142136 1.7320508
r2 2 2.236068 2.4494897
r3 2.6457513 2.8284271 3
-matewmf- as published in STB-56 is about
30 lines long, but can now be written much
more concisely:
*! 1.1.0 NJC 17 November 2005
*! 1.0.0 NJC 25 January 2000
program matewmf
version 8.0
gettoken A 0 : 0
gettoken B 0 : 0, parse(" ,")
syntax , Function(str)
tempname C
mat `C' = `A'
forval i = 1/`=rowsof(matrix(`A'))' {
forval j = 1/`=colsof(matrix(`A'))' {
mat `C'[`i',`j'] = `function'(`A'[`i',`j'])
}
}
mat `B' = `C' /* allows overwriting of either `A' or `B' */
end
from which you can see, as would be expected, that
the problem boils down to a double loop.
Nick
[email protected]
I.A.C. van de Snepscheut
> Is there a simple way to take the sqrt of all the elements in
> a matrix?
*
* 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/
