Re: Control Package Changes May Cause VLFamp Example to Fail

[Thomas D. Dean]

On 2017-10-09 10:54 PM, Thomas D. Dean wrote:
> The VLFamp example fails for control 3.0.0
>
> The problem is at line 217 of VLFamp.m
>
> octave:47> TFnorm
>
> Transfer function 'TFnorm' from input 'u1' to output ...
>
>               2.326e-07 s + 1
>   y1:  -----------------------------
>        1.818e-08 s^2 + 0.01818 s + 1
>
> Continuous-time model.
> octave:48> step(TFnorm,'b')
> out of memory or dimension too large for Octave's index type
> error: called from
>      __sys2tf__ at line 35 column 16
>      tf at line 193 column 16
>      tfdata at line 62 column 9
>      __c2d__ at line 71 column 18
>      c2d at line 82 column 7
>      __time_response__ at line 116 column 7
>      step at line 74 column 10
>
> Tom Dean

On a different system, same version of octave and control, but, with
gnuplot,



>> TFnorm = TFopen/dcgain(TFopen)

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

             2.326e-07 s + 1
 y1:  -----------------------------
      1.818e-08 s^2 + 0.01818 s + 1

Continuous-time model.

>> step (TFnorm, 'b')
error: tf2ss: __sl_td04ad__: TD04AD returned info = 0

Is this one of the cases where step used to simply ignore invalid arguments?

Tom Dean