Add Chua circuit examples, alpha-transform dynamics, and core WDF extensions by frantic0 · Pull Request #5 · gusanthon/pywdf

frantic0 · 2025-11-13T12:52:47Z

This pull request adds support for simulating the Chua circuit in pywdf and introduces a small set of extensions to the core WDF API, along with new examples and documentation updates.

Core API changes (`pywdf/core/wdf.py`)

Add ChuaDiode, a nonlinear negative-resistance element implementing a piecewise-linear I–V characteristic.
Add SeriesVoltage, a two-port series adaptor with an embedded resistive voltage source for injecting voltage impulses (used to excite the Chua circuit, but reusable in other circuits).
Implement an α-transform discretisation option for linear dynamic elements (Capacitor and Inductor), with parameters for selecting between bilinear (Tustin) and backward-Euler behaviour and exploring different stability/accuracy trade-offs.
Add a base-class helper method to convert wave variables to currents, following the WDF parametric definition.

New examples

Add two WDF Chua circuit examples:
- Chua circuit excited by a resistive voltage source.
- Chua circuit excited via the new SeriesVoltage adaptor.
Add basic RLC example circuits: resistor, resistor_series, resistor_parallel, inductor, and capacitor.

Documentation

Add a reference in README.md to the Meerkötter & Scholz paper describing the digital simulation of nonlinear circuits by WDF principles.

Testing

Verified that the new core elements and helpers can be instantiated and used in WDF circuits without errors.
Ran existing example scripts plus the new Chua and basic-circuit examples to confirm they execute and produce reasonable outputs.

… circuit impedance/conductance calculation

…tions

xaviliz · 2025-11-21T11:53:21Z

Hi @frantic0

Thanks a lot for your contribution.
It looks like a really interesting example to include in the library.
It is really exciting that others enlarge this library.

Unfortunately, I am very busy these days.
We are at the end of the course :)
But we have start to revise it.

Hopefully we can give you some feedback soon.

frantic0 · 2025-11-26T11:29:12Z

Thanks so much for the reply @xaviliz, and no worries at all, I completely understand how busy the end of a course can be (it’s a hectic time on my side too!).

I really appreciate you taking the time to look at this. I also wanted to say how much I enjoy pywdf, it’s a fantastic project and a great resource for exploring WDFs in practice.

Happy to make any changes or adjustments once you’ve had a chance to review.

gusanthon · 2025-11-26T21:14:26Z

Hey @frantic0 , thanks so much for the contribution this is great work! Just added a few minor comments but otherwise looks great!

frantic0 · 2025-12-29T12:40:09Z

Hi @gusanthon @xaviliz, I hope you’re both enjoying a good seasonal break. Just checking in on the state of the PR, I’m very happy to make any changes you’d like before it’s ready to merge. Do let me know, please.

gusanthon · 2026-03-03T21:14:39Z

Hey @frantic0 , sorry for the late reply! I left a couple small comments in the review, after that I think it's ready to merge. Thanks again for the contribution!

frantic0 · 2026-03-06T12:25:58Z

Hi @gusanthon thanks, glad that the contribution was found valuable. I can't seem to find any review or comments... Am I missing something?

gusanthon · 2025-11-26T21:04:38Z

pywdf/examples/inductor.py

+        # self.SW1 = Switch(self.S1)
+
+        # init and set circuit
+        super().__init__(self.Vs, self.S1, self.C1)


I think this should be L1 instead of C1?

correct inductor variable in constructor argument

good catch! changed

gusanthon · 2025-11-26T21:06:41Z

pywdf/examples/resistor_parallel.py

        self.R2.set_resistance(new_R)

+
+    def process_sample(self, sample: float) -> float:


I'm getting a ValueError running this, not sure we need to override process_sample here?

correct, we don't need it. I removed it and fixed the problem

gusanthon · 2025-11-26T21:09:10Z

pywdf/examples/voltage_divider.py

+        self.R2.set_resistance(new_R)
+
+
+    def process_sample(self, sample: float) -> float:


same ValueError here, don't think process_sample needs overriding

same problem, we don't need it. I removed it and fixed the problem

gusanthon · 2025-11-26T21:10:13Z

pywdf/core/circuit.py


+
+
+    def process_sample_i_v(self, sample: float) -> float:


Suggested change

def process_sample_i_v(self, sample: float) -> float:

def process_sample_i_v(self, sample: float) -> tuple[float, float, float]:

correct type anotation to tuple of floats

corrected type annotation

gusanthon · 2026-03-06T13:32:47Z

Hi yes @frantic0 sorry about that, looks like I didnt submit the review. Hopefully you can see it now. Thansk again!

correct return type annotation to tuple[float, float, float] Co-authored-by: gusanthon <99610799+gusanthon@users.noreply.github.com>

frantic0 · 2026-03-07T00:12:26Z

hi @gusanthon, thanks a lot for the review and suggestions! I’ve gone through and addressed all the comments in the latest commits. Please let me know if you’d like any further changes.

gusanthon · 2026-03-19T17:41:34Z

test.py

@@ -1,14 +1,25 @@
-from pywdf import RCA_MK2_SEF, TR_808_HatResonator, DiodeClipper
+from pywdf import RCA_MK2_SEF, TR_808_HatResonator, DiodeClipper, VoltageDivider, Chua


test.py is failing, looks like Chua is not exported in __init__.py
also seems like the Chua constructor takes different args

fixed Chua export in init.py and Chua constructor in test.py

gusanthon · 2026-03-19T17:42:47Z

tests/test_newton_raphson.py

+import math
+import numpy as np
+
+from pywdf.core.solver.newton_raphson import newton_raphson


test_newton_raphson.py fails - I don't see newton_rapshon in the solver module?

Added a small sys.path bootstrap at the top of tests/test_newton_raphson.py and tests/runge_kutta.py to allow direct execution

gusanthon · 2026-03-19T17:43:39Z

pywdf/examples/inductor.py

+        if self.frequency != frequency:
+            self.frequency = frequency
+
+            self.L = 1.0 / (np.square(self.twopi * frequency) * self.C)


this is causing AttributeError: '_Inductor' object has no attribute 'C'

gusanthon · 2026-03-19T17:48:58Z

I'm also getting a path issue when plotting in each of voltage_divider.py, resistor_series.py, resistor_parallel.py:
FileNotFoundError: [Errno 2] No such file or directory: '../../tests/resistor_parallel.png'

I also noticed chua_ODE.py in the repo structure but not in the source.

Thanks again for the updates!

…utta.py

frantic0 added 7 commits May 19, 2025 14:18

added wave_to_current method to basedWDF and corrected Short and Open…

f301352

… circuit impedance/conductance calculation

added chua

056f8bb

add all changes to the library and examples

39a9fc3

cleaned up examples and wdf.py extensions

53ba34a

more clean up and update to the README file with this fork's contribu…

c53ab78

…tions

update to the README file

93abc3b

cleaning up for pull request

3473a9c

gusanthon reviewed Mar 6, 2026

View reviewed changes

frantic0 and others added 4 commits March 6, 2026 21:31

Apply suggestion from @gusanthon

49b2eef

correct return type annotation to tuple[float, float, float] Co-authored-by: gusanthon <99610799+gusanthon@users.noreply.github.com>

Address review comments

188f340

Merge branch 'main' of github.com-first:frantic0/pywdf

a090fc0

Address review comments

be0a5e1

gusanthon reviewed Mar 19, 2026

View reviewed changes

frantic0 added 4 commits March 28, 2026 23:46

fix Chua export in __init__.py and Chua constructor in test.py

29abd6c

fix newton_raphson solver and test

832ab41

allow direct execution tests/test_newton_raphson.py and tests/runge_k…

0205caa

…utta.py

fix inductor, voltage divides, resistor series and parallel

6b5a206

		self.R2.set_resistance(new_R)


		def process_sample(self, sample: float) -> float:

	def process_sample_i_v(self, sample: float) -> float:
	def process_sample_i_v(self, sample: float) -> tuple[float, float, float]:

		@@ -1,14 +1,25 @@
		from pywdf import RCA_MK2_SEF, TR_808_HatResonator, DiodeClipper
		from pywdf import RCA_MK2_SEF, TR_808_HatResonator, DiodeClipper, VoltageDivider, Chua

Conversation

frantic0 commented Nov 13, 2025

Core API changes (pywdf/core/wdf.py)

New examples

Documentation

Testing

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xaviliz commented Nov 21, 2025

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frantic0 commented Nov 26, 2025

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frantic0 commented Dec 29, 2025

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gusanthon commented Mar 3, 2026

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gusanthon commented Mar 6, 2026

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gusanthon commented Mar 19, 2026

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Core API changes (`pywdf/core/wdf.py`)

gusanthon commented Nov 26, 2025 •

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frantic0 commented Mar 7, 2026 •

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