Re: [OctDev] control 2.3.53 released

[marco a. <mar...@gm...>]

On 9/3/2012 12:03 PM, Lukas Reichlin wrote:
> On 03.09.2012, at 10:39, Rafael Laboissiere <ra...@la...> wrote:

> Hi Rafael,
>
> You can check whether the observed and expected results are equivalent state-space models (i.e. state-transformation, see command prescale for formulae). This can be done, e.g., by inspection of the Hankel singular values (command hsvd), time response (step, impulse) or frequency response (sigma).
> If they are the same, there should be nothing to worry about. If you want the same results, use Reference BLAS (and LAPACK) from www.netlib.org instead of ATLAS which you are probably using. The SLICOT authors recommend the use of the reference implementations. Correct results are more important than minor speed advantages of automatically tuned linear algebra software, aren't they? :-)
>
> Regards,
> Lukas
>

Lukas,
there is no guarantee to have the "expected" result
also with the reference lib.

Using Lapack 3.4.1 on cygwin


  test /home/marco/octave/control-2.3.53/@lti/minreal.m
   ***** assert (Ar, Ae, 1e-4);
!!!!! test failed
assert (Ar,Ae,1e-4) expected
    1.00000  -0.03930  -0.09800  -0.10660   0.07810  -0.23300   0.07770
    0.00000   1.03120   0.27170   0.26090  -0.15330   0.67580  -0.35530
    0.00000   0.00000   1.38870   0.66990  -0.42810   1.63890  -0.76150
    0.00000   0.00000   0.00000  -1.21470   0.24230  -0.97920   0.47880
    0.00000   0.00000   0.00000   0.00000  -1.05450   0.50350  -0.27880
    0.00000   0.00000   0.00000   0.00000   0.00000   1.63550  -0.43230
    0.00000   0.00000   0.00000   0.00000   0.00000   0.00000   1.00000
but got
    1.00000   0.03935   0.09802  -0.10656   0.07805  -0.23302   0.07773
    0.00000   1.03122   0.27169  -0.26093   0.15327  -0.67578   0.35529
    0.00000   0.00000   1.38869  -0.66991   0.42806  -1.63894   0.76153
    0.00000   0.00000   0.00000   1.21467  -0.24232   0.97919  -0.47884
    0.00000   0.00000   0.00000   0.00000   1.05454  -0.50348   0.27881
    0.00000   0.00000   0.00000   0.00000   0.00000   1.63547  -0.43234
    0.00000   0.00000   0.00000   0.00000   0.00000   0.00000   1.00000
maximum absolute error 3.27784 exceeds tolerance 0.0001

so we need to define a different test methodology

Regards
Marco