Oct2py binary operator '*' not implemented

Question

I'm using oct2py to execute an octave function from python, and I get the following error:

oct2PyError: Octave evaluation error: error: binary operator '*' not implemented for 'int64 scalar' by 'complex matrix' operations

In python, im just calling the function with:

from oct2py import octave
results = octave.myOctaveFunction(parameters)

In debugging of myOctaveFunction, I think the error is in the code:

slc=interpft(slc, OSF*lines, 1);

where:

slc is a complex matrix of size = [241,41] (double precision)
OSF is an oversampling factor. OSF = 16 (int64)
lines is the number of rows of slc matrix. lines = 241 (scalar)
interpft function: https://www.mathworks.com/help/matlab/ref/interpft.html

Edit: detailed traceback:

Traceback (most recent call last):

  File "/home/ezaqui/Papyrus/plugins/org.python.pydev_5.1.2.201606231256/pysrc/_pydevd_bundle/pydevd_exec.py", line 3, in Exec
    exec exp in global_vars, local_vars
  File "<console>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/oct2py/dynamic.py", line 96, in __call__
    return self._ref().feval(self.name, *inputs, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/oct2py/core.py", line 369, in feval
    store_as=store_as, plot_dir=plot_dir)
  File "/usr/local/lib/python2.7/dist-packages/oct2py/core.py", line 568, in _feval
    raise Oct2PyError(msg)
Oct2PyError: Octave evaluation error:
error: binary operator '*' not implemented for 'int64 scalar' by 'complex matrix' operations

Your error says you are multiplying a scalar by a complex matrix but, in your description of that line, the only things getting multiplied are two scalars. I would guess either that is not the offending line or `lines` is not actually a scalar. — FamousJameous, Apr 26 '17 at 17:23
I think the multiplication is done inside of interpft function. The code crash exactly before that line — eduardosufan, Apr 26 '17 at 17:25

Tasos Papastylianou · Accepted Answer · 2017-04-30T00:52:51.963

tl;dr:

slc=interpft(slc, double(OSF*lines), 1);

Explanation:

You are trying to multiply a complex matrix with an int64 type. Apparently the multiplication operation is not defined for this type in octave; it's only defined for doubles.

>> int64(5) * [1 + 1i]
error: binary operator '*' not implemented for 'int64 scalar' by 'complex scalar' operations

>> double(5) * [1 + 1i]
ans =  5 + 5i

So this is not an oct2py problem specifically. Just ensure that OSF is converted to double before the multiplication with a complex matrix in your octave function instead.

As for why you're getting a multiplication with a complex in the first place, I suspect the interpft function takes the result of your multiplication and multiplies a complex matrix somewhere. In octave, as it turns out, multiplying an int64 with a double results in an int64:

>> class(int64(5) * double(5))
ans = int64

Oct2py binary operator '*' not implemented

1 Answers1