# RE: st: RE: use Mata to calculate the eigenvalues of the matrix

 From "Nick Cox" To Subject RE: st: RE: use Mata to calculate the eigenvalues of the matrix Date Sun, 8 Mar 2009 19:39:58 -0000

To the all-knowing, the signal that you were working with 126 rows
should have been enough information.

Look again at the help for -invvech()-:

"invvech(v):
v:   (n*(n+1)/2) x 1
result:   n x n

invvech(v) aborts with error if v does not have 0, 1, 3, 6, 10, ...
rows."

126 rows does not match the form n(n+1)/2 needed to get a square matrix
out of -invvech()-. 120 rows or 136 rows would work, but not 126.

Nick
n.j.cox@durham.ac.uk

jjc.li@utoronto.ca

M[126,16]
halflnpllnpl	halflnpklnpk	halflnpmlnpm	halflnpelnpe halflnqlnq
halftt	h11
r1     55.698589	3.6893287	7.4771399	18.149426
50.228111	.5	-.08101387
r2     55.925751	4.2461691	7.5901814	17.818066
50.520424	2	-.07783842
r3     55.890606	5.0145068	8.2533903	17.348637
49.332706	4.5	-.06268991
r4      55.84235	6.8188863	8.1996651	17.327908
48.37619	8	-.04702383
r5     55.992165	11.663833	8.5312452	17.296404
48.428661	12.5	-.04062275
r6     56.231369	6.2716689	9.8907461	17.231161
47.613789	18	-.02769819
..................................................................omitte
d
r125	59.936024	6.0803957	8.1817226	11.001316
48.745419	144.5	-.10420492
r126	62.886497	5.7553158	8.4018955	11.243708
47.780876	162	-.11177195

h21	h31	h41	h22	h32	h42	h33
r1	.0058905	.04511028	.02139651	-.03382511
.03340751	-.0086062	-.10248575
r2	.00514857	.05326439	.02111828	-.03219827
.03637264	-.00870738	-.07974763
....................................................................omit
ted
r126	.01168905	.07623301	.02273416	-.0396621
.03610333	-.00847654	-.10935289

h43           h44
r1    -.00469169     -.0092736
r2    -.00357977     -.0086003
....................................................................omit
ted
r126    -.00577275     -.0086003

Quoting Nick Cox <n.j.cox@durham.ac.uk>:

> The code you show won't work, so it does not explain much. But your
> regions X years set-up should be irrelevant. But show us the matrix:
>
> . mat li M
>
> Nick
> n.j.cox@durham.ac.uk
>
> jjc.li@utoronto.ca
>
> Thank you martin and Nick!
>
> My matrix M can be computed as follows:
>
> 11
> 21  22
> 31  32  33
> 41  42  43  44
>
>
> I used the coefs' point estimates available in ereturn list computed
> from 126 time-series observations and calculted the elements of matrix
> for each time period:
>
> generate 11=...
> generate 21=...
> ...
> generate 44=...
> mkmat h*, mat (M)
>
> Then the mata codes I mentioned in previous posting.
>
> But the 126 obervations are composed of 7 regions, 18 years
> (7*18=126). Does it cause the
> problem?
>
> Quoting Nick Cox <n.j.cox@durham.ac.uk>:
>
>> Mata never even tries to calculate any eigenvalues, as before that
> point
>> -invvech()- chokes on what you feed it.
>>
>> To hear more, you need to tell us more about your matrix M.
>>
>> As Martin said, -moremata- is not invoked here and so appears
> irrelevant
>>
>> Nick
>> n.j.cox@durham.ac.uk
>>
>> jjc.li@utoronto.ca
>>
>> I am tring to use Mata to calculate the eigenvalues of the matrix,
but
>> there is some problems. First, I installed the moremata package by
Ben
>> Jann. Then, when I type:
>>
>> mata:
>> M = st_matrix("M")
>> lambda = J(cols(M), 4, .)
>> for(t=1; t<=cols(M); t++) {
>> mt = invvech(M[., t])
>> lambda[t, .] = symeigenvalues(mt)
>> }
>> lambda
>> end
>>
>> The output shows:
>>
>>                 invvech():  3498  invalid vech
>>                   <istmt>:     -  function returned error
>>
>
------------------------------------------------------------------------
>> ------------------------------------
>> r(3498);
>>
>> .
>> . lambda
>> unrecognized command:  lambda
>> r(199);
>>
>> .
>> . end
>> unrecognized command:  end
>> r(199);
>>
>>
>> if I type:
>> mata:
>> M = st_matrix("M")
>> lambda = J(cols(M), 4, .)
>> for(t=1; t<=cols(M); t++) {
>> mt = invvech(M[., t])
>> lambda[t, .] = symeigenvalues(mt)
>> }
>>
>> the output shows:
>>
>>                 invvech():  3498  invalid vech
>>                   <istmt>:     -  function returned error
>>
>
------------------------------------------------------------------------
>> ------------------------------------
>> r(3498);
>>
>>
>> Do you know where's the error of my codes?

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