Uli Kohler <[email protected]> and Magda Luniak <[email protected]>
are having problems getting their code to work after putting it in a
.mlib library.
They have a do-file which compiles all the code,
. do lsq.mata
and I assume file lsq.mata also creates the library. The library, they
report, is named lsq.mata.
They have an ado file, sqom.ado, which works just fine right after
-do lsq.mata-,
. do lsq.mata
. sqom
<expected output appears>
but later, or after a -clear-, if they run -sqom-, they get an error message,
. sqom
<istmt>: 3499 sqomref() not found
r(3499);
So what could be going on? There are two possibilities,
1. The have not included everything in the library that they
thought they did (in particularly, they left out -sqomref()-, or
2. The computer is not even looking in the library lsq.mata.
I rather like #2.
Where is the file lsq.mata? That is, in which directdory? When was it
put there? Even if lsq.mata is located in some official directory
(such as PERSONAL), it it was put there after Stata was already
running, Mata would not know to look there, and in that case, you must type
. mata mlib index
Don't do that yet, though. First type,
. mata mlib query
to find out what libraries Mata is searching.
Mata's library search
---------------------
Libraries in Mata start with the letter "l" (el) and end in ".mlib".
Unlike with ado-files, however, Mata does not search for them any time
it cannot find something it needs.
Instead, Mata forms a list of the libraries. It does that the first
time -mata- is invoked in a Stata session. Mata also does it whenever
you type
: mata mlib index
to the Mata prompt.
I do not recommend you put -mata: mata mlib index- in your ado-file, because
the command can take a long time to run, especially on laptops.
Anyway, when I type -mata mlib query- on my computer, here is the result:
: mata mlib query
.mlib libraries to be searched are
lmatabase;lmataado
I get the same result if I type -mata mlib index- because I only have
two libraries that came with Mata on my computer.
When Uli or Magda type -mata mlib query-, they hope to see something like
: mata mlib query
.mlib libraries to be searched are
lmatabase;lmataado;lsqom
If they do not, then Mata is not looking there. Assuming the library is
around where Mata can find it, typing
: mata mlib index
.mlib libraries to be searched are now
lmatabase;lmataado;lsqom
should fix the problem. Assuming the library is in some official place
(such as PERSONAL), the next time they want to use -sqom-, they will not
have to type -mata mlib index- because the library will be found automatically
the first time Mata is invoked.
Anyway, the unfound library is my favorite explanation right now.
I especially like it because it might explain the apparent random
behavior they described. Imagine they have old versions of some routines
laying around in .o files. Not finding the library, Mata might latch onto
those.
My second favorite explanation is that the library does not contain
everything Uli and Magda think it contains, and I'll mix that with
old .o files laying around. The next time Uli or Magda get one of the
longer error messages, such as
. sqom
hashing(): 3499 elemlist() not found
sqomref(): - function returned error
<istmt>: - function returned error
r(3499);
I suggest they explore such how -sqomref()- and -hashing()- were found,
which they can do by typing
. mata: mata which sqomref()
. mata: mata which hashing()
They might be in for a surprise.
When I create a Mata library, here is how I organize my file:
----------------------------- example.mata --- BEGIN ---
version 9.2
clear
capture erase "`c(sysdir_personal)'/lexample.mlib"
// ---------------------------- code begins
mata:
function ...
{
...
}
...
end
// ---------------------------- code ends
mata:
mata mlib create lexample, dir(PERSONAL)
mata mlib add lexample *(), dir(PERSONAL)
mata describe using lexample
end
----------------------------- example.mata --- END ---
This way, I know I leave nothing out.
In the example above, I create the library in my PERSONAL directory.
-- Bill
[email protected]
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