Ngspice version 31 support

[matthuszagh]

Would it be possible to add Ngspice version 31 support? Are there any specific hurdles to supporting it, or it just hasn't been tested yet?

Steps to reproduce the behaviour

$ python
>>> from PySpice.Spice.NgSpice.Shared import NgSpiceShared
>>> ngspice = NgSpiceShared.new_instance()
Unsupported Ngspice version 31

Using python 3.7.6 and PySpice master.

[stuarteberg]

Looks like that's just a warning. Aside from that warning, did you notice any other problems with ngspice 31? (I'm not a PySpice dev, I'm just curious.)

[matthuszagh]

I didn’t find any specific issues, was mostly just curious if the dev had found issues or just hadn’t tested it yet.

[stuarteberg]

Looks like it ought to work, as long as these fields haven't changed. They need to match this enum, and they do.

I've opened PR #186 to eliminate the warning.

[alexmyczko]

This thing outputs all 0s and that warning

import numpy as np
import matplotlib.pyplot as plt

from PySpice.Spice.Netlist import Circuit
from PySpice.Unit import *

circuit = Circuit('Low-Pass RC Filter')

circuit.SinusoidalVoltageSource('input', 'in', circuit.gnd, amplitude=1@u_V)
R1 = circuit.R(1, 'in', 'out', 1@u_kΩ)
C1 = circuit.C(1, 'out', circuit.gnd, 1@u_uF)

simulator = circuit.simulator(temperature=25, nominal_temperature=25)
analysis = simulator.ac(start_frequency=1@u_Hz, stop_frequency=1@u_MHz, number_of_points=1,  variation='dec')

print(np.absolute(np.array(analysis.out)))

instead I'm expecting something like this:

Node name 'in' is a Python keyword
[9.9998027e-01 9.9803191e-01 8.4673303e-01 1.5717673e-01 1.5913479e-02
1.5915474e-03 1.5915494e-04]

[stuarteberg]

Do you know if the behavior is different for ngspice 30?

[alexmyczko]

Dunno, I'm on Ubuntu 18.04 and backported the sid https://packages.debian.org/search?keywords=ngspice 31.3, can try the buster 30.2...

Works:

$ python3 PySpice_min_working_example.py 
Node name 'in' is a Python keyword
[  9.99980271e-01   9.98031914e-01   8.46733034e-01   1.57176733e-01
   1.59134790e-02   1.59154739e-03   1.59154937e-04]

[stuarteberg]

Huh. I can also reproduce the difference in behavior using your example.
Unfortunately, I don't have the knowledge or resources to investigate this.

With ngspice 30:

$ ngspice --version | head -n1
ngspice compiled from ngspice revision 30

$ pip list | grep PySpice
PySpice         1.3.2

$ python /tmp/example.py
Node name 'in' is a Python keyword
[9.9998027e-01 9.9803191e-01 8.4673303e-01 1.5717673e-01 1.5913479e-02
 1.5915474e-03 1.5915494e-04]

But with ngspice 31:

$ ngspice --version | head -n1
ngspice compiled from ngspice revision 31

$ pip list | grep PySpice
PySpice         1.3.2

$ python /tmp/example.py
Node name 'in' is a Python keyword
Unsupported Ngspice version 31
[0. 0. 0. 0. 0. 0. 0.]

[brainstorm]

@alexmyczko I've recently jumped to ngspice 31 and while testing I found this issue and playing with your example I identified a couple of issues with your program, here's a slightly revised version, easier to debug:

#!/usr/bin/env python

import numpy as np
import matplotlib.pyplot as plt

from PySpice.Spice.Netlist import Circuit
from PySpice.Unit import u_V, u_kOhm, u_uF, u_Hz, u_MHz

circuit = Circuit('Low-Pass RC Filter')

circuit.SinusoidalVoltageSource('input', 'inp', circuit.gnd, amplitude=1@u_V)
R1 = circuit.R(1, 'inp', 'out', 1@u_kOhm)
C1 = circuit.C(1, 'out', circuit.gnd, 1@u_uF)

simulator = circuit.simulator(temperature=25, nominal_temperature=25)
analysis = simulator.ac(start_frequency=1@u_Hz, stop_frequency=1@u_MHz, number_of_points=1,  variation='dec')

print(analysis._simulation._ngspice_shared._stdout)
#print(np.absolute(np.array(analysis.out)))

But in essence, this is what happens under the hood on ngspice side:

./test_ngspice30.py 
['Circuit: Low-Pass RC Filter', 'Error on line 2 :', 'vinput inp 0 dc 0v ac sin(0v 1v 50hz 0s 0hz)', 'parameter value out of range or the wrong type', 'Doing analysis at TEMP = 25.000000 and TNOM = 25.000000', 'Reference value :  1.00000e+00\r', 'No. of Data Rows : 7']

Hope that helps! ;)

[alexmyczko]

Frankly it wasn't my example, but a persons that I support, I sent them a link, however I'm not sure they will read it... But thanks!

[Lewous]

The version warning seems comes from here, and have been fixed (but not on pypi).
I tried reinstall ngspice-30.pkg over version 31 on mac OS, but failed. Some examples still shows output is zero ( I got figures plotted but only straight lines on there).

the PySpicePro mentioned that it only support ngspice-30, there might be some compatibility problems.

[FabriceSalvaire]

fixed on a6476cf but not SIN folks