st: Mata and do files

[Alex Olssen <alex.olssen@gmail.com>]

Hi everyone,

Apologies to anybody who gets this message twice - I just got an email
from Stata telling me my first message was bounced.  I checked the
archive and it doesn't appear to have arrived correctly.  In any
case...

I am trying to learn some Mata and am having difficult running Mata
code from a do file.

For example I can use the following code interactively, but if I try
run it from the do-file editor I get error r(3000).  I have looked
around for an answer in [M] and the Statalist archives to no avail.

sysuse auto, clear
mata
real scalar theta()
{
st_view(a = ., ., "price length weight")
a_cov = variance(a)
a_eigen = symeigensystem(a_cov, X = ., L = .)
return(L[1]/sum(L))
}
theta()

Any help would be greatly appreciated.

Cheers,
Alex Olssen
*
*   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/