zp2tf() triggers error: 'is_real_vector' undefined

Question

This is the code and the error it produces:

octave:1> z = [-1;1];
octave:2> p = [0.5+0.5j;0.5-0.5j];
octave:3> k = 1;
octave:4> n = 100;
octave:5> pkg load signal
octave:6> [b,a] = zp2tf(z,p,k);
error: 'is_real_vector' undefined near line 38 column 15
error: called from:
error:   /home/raffael/octave/control-2.6.2/@tfpoly/tfpoly.m at line -1, column -1
error:   /home/raffael/octave/control-2.6.2/__vec2tfpoly__.m at line 32, column 7
error:   /home/raffael/octave/control-2.6.2/@tf/tf.m at line 223, column 13
error:   /home/raffael/octave/control-2.6.2/zpk.m at line 101, column 11
error: evaluating argument list element number 1
error:   /home/raffael/octave/signal-1.3.0/zp2tf.m at line 41, column 12

I use Octave 3.8.1 on Ubuntu 14.04.

According to this opened and closed bug report this error might be caused by flawed installation.

So I reinstalled Octave and the signal package (as usual using apt-get):

sudo apt-get update
sudo apt-get upgrade
sudo apt-get remove octave
sudo apt-get install octave
sudo apt-get install octave-signal

Can somebody confirm with Octave 3.8.1 that this is a bug or is my installation process the problem?

Answer 1

This works fine in my system using my own build of Octave and packages installed via pkg.

From the errors message, it seems that you are using packages installed locally but at the same time, you mention installing them via Ubuntu's package manager. I'd suggest check your ~/octave/ directory and remove it if you're sticking with Ubuntu's package manager. From my experience is not a good idea to use both.