How to realize a transfer function with higher order of numerator than denominator in octave?

Question

a=1

% Construct the trasfer function
num=[a 1 3]
den=[1 2 10]
G=tf(num,den)

% Impulse response
impulse(G)

% Step response
step(G)

When I click on 'run' this error appears "error: Order numerator >= order denominator"

Answer 1

If you follow the error on the terminal, it suggests that line 95 in imp_invar.m of the control package is to blame. (if you don't know where this was installed, you can find out by typing pkg list in your terminal)

If you convert this error to a warning, the code continues. Obviously you do so at your own risk. I would make a backup of the original .m file just in case.

Note that the same code run on matlab does not issue any error or warning (which is odd in itself, given the stark note about invalid impulse invariance in this scenario from octave ... there is a reference quoted inside imp_invar.m if you're interested.)