Install Slycot on Windows 11 failing

[TomLXXVI]

I use Pycharm on a Windows 11 computer. For a new project I wanted to use the Python Control Systems library. I created a virtual environment using conda. With the virtual environment being active, I installed the package with the instruction conda install -c conda-forge control slycot on the command line. The version of control is 0.9.4, and the version of slycot is 0.5.4.

Somewhere in my code I call ct_ss, _ = ct.canonical_form(self._ct_state_space, form='modal') (with ct being a short-cut for the control package, i.e., import control as ct). The function canonical_form with parameter form set to string "modal", seems to use the underlying slycot package. And it's here where trouble starts. I get this error message:

Traceback (most recent call last):
  File "C:\Users\Tom\anaconda3\envs\control-engineering\Lib\site-packages\control\canonical.py", line 328, in _bdschur_condmax_search
    from slycot import mb03rd
  File "C:\Users\Tom\anaconda3\envs\control-engineering\Lib\site-packages\slycot\__init__.py", line 16, in <module>
    from .analysis import ab01nd, ab05md, ab05nd, ab07nd, ab08nd, ab08nz
  File "C:\Users\Tom\anaconda3\envs\control-engineering\Lib\site-packages\slycot\analysis.py", line 22, in <module>
    from . import _wrapper
ImportError: DLL load failed while importing _wrapper: Kan opgegeven module niet vinden.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\Tom\PycharmProjects\control-engineering\tryouts\tryout_08.py", line 7, in <module>
    ss = ss.reform('parallel')
         ^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Tom\PycharmProjects\control-engineering\python_control\core\state_space.py", line 268, in reform
    ct_ss, _ = ct.canonical_form(self._ct_state_space, form='modal')
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Tom\anaconda3\envs\control-engineering\Lib\site-packages\control\canonical.py", line 66, in canonical_form
    return modal_form(xsys)
           ^^^^^^^^^^^^^^^^
  File "C:\Users\Tom\anaconda3\envs\control-engineering\Lib\site-packages\control\canonical.py", line 522, in modal_form
    amodal, tmodal, _ = bdschur(xsys.A, condmax=condmax, sort=bd_sort)
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Tom\anaconda3\envs\control-engineering\Lib\site-packages\control\canonical.py", line 449, in bdschur
    amodal, tmodal, blksizes, eigvals = _bdschur_condmax_search(
                                        ^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Tom\anaconda3\envs\control-engineering\Lib\site-packages\control\canonical.py", line 330, in _bdschur_condmax_search
    raise ControlSlycot("can't find slycot module 'mb03rd'")
control.exception.ControlSlycot: can't find slycot module 'mb03rd'

I have no clue how to fix this issue myself. I tried to build slycot from source, but without success. I also found that when I install with conda install -c "conda-forge/label/cf202003" control slycot the error does not appear, but then the numbers in the matrices returned from e.g. ct.tf2ss() and ct.canonical_form() look terrible.

Some help would be very welcome.

[bnavigator]

Hi, this looks like another of those windows/conda install hiccups. Is your conda up to date and which python do you use?

Can you boil this down to a minimum slycot install check?

Within the control-engineering environment, can you import slycot or does it already throw a similar error? Is the dll/pyd installed correctly in the site-packages? Do you have MKL or openBLAS correctly installed? (For the latter being relevant, see #219 )

[TomLXXVI]

I use conda 23.9.0 and for this project I use Python 3.11.6. When I import slycot in a script (import slycot), the same error occurs:

Traceback (most recent call last):
  File "C:\Users\Tom\PycharmProjects\control-engineering\tryouts\tryout_08.py", line 3, in <module>
    import slycot
  File "C:\Users\Tom\anaconda3\envs\control-engineering\Lib\site-packages\slycot\__init__.py", line 16, in <module>
    from .analysis import ab01nd, ab05md, ab05nd, ab07nd, ab08nd, ab08nz
  File "C:\Users\Tom\anaconda3\envs\control-engineering\Lib\site-packages\slycot\analysis.py", line 22, in <module>
    from . import _wrapper
ImportError: DLL load failed while importing _wrapper: Kan opgegeven module niet vinden.

The ImportError tells that the module _wrapper cannot be found. When I look in the slycot package installed in my conda environment, there is no file _wrapper present. However, there is a PYD file called _wrapper.cp311-win_amd64.pyd.

[TomLXXVI]

I've read issue #219. At the end pichim mentioned what worked for him:

conda update --all
conda create -n control-env-3-12 pytest numpy scipy control matplotlib ipykernel slycot python=3.12

I tried almost exactly the same, except I use the regular conda that is installed with Anaconda Navigator. So I wrote:

conda update --all
conda create -c conda-forge -n control-env-3-12 pytest numpy scipy control matplotlib ipykernel slycot pint sympy python=3.12

(I've just added channel conda-forge, and I also need pint and sympy in my project).

In this new virtual environment, called control-env-3-12, package slycot is working now (this means the ImportError has disappeared).

[bnavigator]

Closing as duplicate of #219.