Some other strange occasions where I used to get errors about "no
matrices in this context" are computations of traces or
determinants... don't remember exactly, but I had to use an extra
matrix with a single element that would contain the trace of another
matrix, and the latter one could be used in scalar computations. Now
with Mata, of course, I won't bother doing any matrix manipulations in
Stata.
On 5/31/07, Nick Cox <n.j.cox@durham.ac.uk> wrote:
I think you are being bitten by code that
tests to see whether you are trying to
-display- the whole of a matrix. You
are, but it's reasonable to ask for a -display-
of the whole of a matrix which is just 1 X 1.
That's my guess. I can't see inside the code
that is behind this error report.
Nick
n.j.cox@durham.ac.uk
Steven Samuels
> Can anyone explain why I get the following error? How can I access
> the elements of the matrix which generates the error?
> Program:
> /************************************/
> webuse nhanes2, clear
> svyset
> svy : mean height
> ereturn list
> matrix list e(V_srs)
> di el(e(V_srs),1,1) //OKAY
>
> matrix list e(b)
> di el(e(b),1,1) //GENERATES ERROR
> /*************************************/
>
> Log:
> webuse nhanes2, clear
>
> . svyset
>
> pweight: finalwgt
> VCE: linearized
> Strata 1: strata
> SU 1: psu
> FPC 1: <zero>
>
> . svy : mean height
> (running mean on estimation sample)
>
> Survey: Mean estimation
>
> Number of strata = 31 Number of obs = 10351
> Number of PSUs = 62 Population size = 1.2e+08
> Design df = 31
> --------------------------------------------------------------
> | Linearized
> | Mean Std. Err. [95% Conf. Interval]
> -------------+------------------------------------------------
> height | 168.4599 .1466103 168.1609 168.7589
> --------------------------------------------------------------
>
> . ereturn list
>
> scalars: [OUTPUT SKIPPED]
> macros: [OUTPUT SKIPPED]
>
> matrices:
> e(b) : 1 x 1
> e(V) : 1 x 1
> e(_N_subp) : 1 x 1
> e(V_srs) : 1 x 1
> e(_N) : 1 x 1
> e(error) : 1 x 1
>
> functions: [OUTPUT SKIPPED]
>
> . matrix list e(V_srs)
>
> symmetric e(V_srs)[1,1]
> height
> height .00908828
>
> . di el(e(V_srs),1,1) //OKAY
> .00908828
>
> . matrix list e(b)
>
> symmetric e(b)[1,1]
> height
> y1 168.45989
>
> . di el(e(b),1,1) //GENERATES ERROR
> matrix operators that return matrices not allowed in this context
> r(509);
*
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--
Stas Kolenikov
http://stas.kolenikov.name
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