[Octave-bug-tracker] [bug #45336] control 2.8.2 - error on MIMO tf multiply

[Nick Jankowski]

Follow-up Comment #4, bug #45336 (project octave):

just grabbed the revised mpower.m file.  the code below in the original error
report works. I noticed all the warnings about SS conversion disappeared.
a1**n seemed well behaved out through n=200

I did try a1*a1, a1*a1*a1... since only mpower changed, that still gave the
same warnings and odd results at n=3, error at n=4.  so it doesn't seem
restricted to mpower



>> a1**4

Transfer function 'ans' from input 'u1' to output ...

      97 s^4 + 6816 s^3 + 1.279e+005 s^2 + 6.083e+005 s + 3.318e+005
 y1:  --------------------------------------------------------------
            s^4 - 96 s^3 + 3456 s^2 - 5.53e+004 s + 3.318e+005

      14 s^5 + 1320 s^4 + 3.802e+004 s^3 + 3.456e+005 s^2 + 6.636e+005 s -
3.969e-005
 y2: 
-------------------------------------------------------------------------------
                    s^4 - 96 s^3 + 3456 s^2 - 5.53e+004 s + 3.318e+005

Transfer function 'ans' from input 'u2' to output ...

      672 s^3 + 3.11e+004 s^2 + 3.318e+005 s + 6.636e+005
 y1:  ---------------------------------------------------
      s^4 - 96 s^3 + 3456 s^2 - 5.53e+004 s + 3.318e+005

      97 s^4 + 6816 s^3 + 1.279e+005 s^2 + 6.083e+005 s + 3.318e+005
 y2:  --------------------------------------------------------------
            s^4 - 96 s^3 + 3456 s^2 - 5.53e+004 s + 3.318e+005

Continuous-time model.


>> a1*a1*a1*a1
warning: tf: converting to minimal state-space for MIMO TF interconnections
warning: called from
    __sys_connect__ at line 115 column 5
    mtimes at line 58 column 7
warning: tf: converting to minimal state-space for MIMO TF interconnections
warning: tf: converting to minimal state-space for MIMO TF interconnections
error: subscript indices must be either positive integers less than 2^31 or
logicals
error: called from
    __sys2ss__> at line -1 column -1
    __sys2ss__ at line 50 column 10
    ss at line 175 column 17
    __sys_connect__ at line 116 column 9
    mtimes at line 58 column 7
error: evaluating argument list element number 1
error: called from
    __sys_connect__ at line 116 column 9
    mtimes at line 58 column 7
error: evaluating argument list element number 1
error: called from
    __sys_connect__ at line 116 column 9
    mtimes at line 58 column 7


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