OSError: cannot load library ngspice.dll': error 0x7e

[HR42]

Environment (OS, Python version, PySpice version, simulator)

Win10.0.19041 Python 3.8.5 (tags/v3.8.5:580fbb0, Jul 20 2020, 15:57:54) [MSC v.1924 64 bit (AMD64)] on win32 PySpice 1.4.3 NgSpice

Expected Behaviour

The ngspice.dll should load without an error.

Actual Behaviour

Traceback (most recent call last): File "test_pyspice.py", line 16, in simulator = circuit.simulator(temperature=25, nominal_temperature=25) File "C:\Python38\lib\site-packages\PySpice\Spice\Netlist.py", line 1299, in simulator return CircuitSimulator.factory(self, *args, **kwargs) File "C:\Python38\lib\site-packages\PySpice\Spice\Simulation.py", line 1119, in factory return sub_cls(circuit, *args, **kwargs) File "C:\Python38\lib\site-packages\PySpice\Spice\NgSpice\Simulation.py", line 99, in init self._ngspice_shared = NgSpiceShared.new_instance() File "C:\Python38\lib\site-packages\PySpice\Spice\NgSpice\Shared.py", line 452, in new_instance instance = cls(ngspice_id=ngspice_id, send_data=send_data, verbose=verbose) File "C:\Python38\lib\site-packages\PySpice\Spice\NgSpice\Shared.py", line 480, in init self._load_library(verbose) File "C:\Python38\lib\site-packages\PySpice\Spice\NgSpice\Shared.py", line 540, in _load_library self._ngspice_shared = ffi.dlopen(self.library_path) File "C:\Python38\lib\site-packages\cffi\api.py", line 150, in dlopen lib, function_cache = _make_ffi_library(self, name, flags) File "C:\Python38\lib\site-packages\cffi\api.py", line 832, in _make_ffi_library backendlib = _load_backend_lib(backend, libname, flags) File "C:\Python38\lib\site-packages\cffi\api.py", line 828, in _load_backend_lib return backend.load_library(path, flags) OSError: cannot load library 'C:\Python38\lib\site-packages\PySpice\Spice\NgSpice\Spice64_dll\dll-vs\ngspice.dll': error 0x7e

Steps to reproduce the behaviour

I try to run the "Resistor Bridge" example on a fresh installation. I have installed pyspice direct with "pip install pyspice". Afterwards I have run "pyspice-post-installation --install-ngspice-dll". The installation steps have processed without any error. The test "pyspice-post-installation --check-install" gives the same error as shown above.

Do you have any hint how to solve this problem? I want to avoid Anaconda, hence the direct installation with pip. As far as I understand the docs this should also be possible?

Regards HR42

[HR42]

Oh, I found the solution: The NgSpice DLL folder must be on the windows path. Fortunately this can be made within the python script: In my case it is:

import os
os.environ["path"] += os.pathsep + r"C:\Python38\lib\site-packages\PySpice\Spice\NgSpice\Spice64_dll\dll-vs"

With this modification the example works as expected.

A specific hint might be helpful when this particular exception occurs? E.g. "Please ensure that the DLL folder is on the windows PATH." Also a short note in the documentation would be very helpful: https://pyspice.fabrice-salvaire.fr/releases/v1.4/installation.html#on-windows

Regards HR42

[OK83]

For me I solved solved this with followed steps :

1. install visual studio code
2. create venv
3. install al needed python libs in venv (numpy, matplotlib, pyspice(don't know if it is needed))
4. change intepreter in visual studio code
5. in venv run : pyspice-post-installation --install-ngspice-dll
6. in venv run : pyspice-post-installation --check-install -> PySpice should work as expected

[sebrupi]

For me i solved it with:

run this 2 comands over the Terminal:

1. cd in to --> cd C:\Users\YOUR_PC_NAME\AppData\Roaming\Python\Python39\Scripts

2. run this comand --> .\pyspice-post-installation --install-ngspice-dll