Dune

SPICE, reborn in Rust. Dune is a faithful rewrite of Berkeley's SPICE3f5 circuit simulator: the same netlists, the same defaults, the same numbers — validated circuit by circuit against ngspice — with a clean engine you can call from Python, R, JavaScript or C.

Dune is a derived work: the engine is a translation of the SPICE3f5 sources of the University of California, Berkeley, and some parts (BSIM3v3.3, the .sp analysis, the operating-point fallback chain, .measure, the transient noise sources and the revisions of several device routines) are derived from ngspice release 47. See Credits and lineage and NOTICE.

Site: milkway.github.io/dune · Examples gallery — every corpus circuit, simulated · Known differences

Packages

One engine, the same numbers from every one of them.

How it fits together

A circuit arrives as a SPICE deck or as a schematic written in pic. dune-core is the only place where circuits are solved; every package is an interface to it.

Every point of every analysis is a Newton–Raphson loop: linearize the devices, solve the linear system, test convergence at SPICE's own tolerances. The sources of both diagrams are pic figures in site/diagrams.

What's inside

• Every SPICE3f5 device and analysis: R C L K, V/I sources, E F G H, diode, BJT (Gummel–Poon), MOS levels 1–6, BSIM1/2, JFET, MESFET, switches, ideal and lossy (LTRA) transmission lines, .subckt — and .OP .DC .AC .TRAN .PZ .NOISE .DISTO .TF .SENS. Plus BSIM3v3.3 and S-parameter analysis (.sp), both translated from the ngspice-47 sources.
• Oracle-tested: nothing ships until every corpus circuit matches pinned ngspice-47 goldens point by point, at SPICE's own tolerances (reltol/abstol/vntol). Deliberate divergences are documented in corpus/KNOWN_DIFFS.md, each behind a measured gate.
• Schematics in, waveforms out: Dune reads figures written in rpic's pic language and extracts runnable decks (dune pic figure.pic); the same engine powers the Simulate panel in rpic Studio, all client-side WebAssembly.
• Rawfiles in SPICE3's own binary and ASCII formats, so existing viewers read them unchanged.
• A more accurate transient by default: .tran integrates with TR-BDF2, an L-stable method that does not ring and, on the corpus, is closer to the converged answer than the trapezoidal rule at the same step; a switch flips at the instant its control crosses the threshold, not at the first timepoint past it. .options compat=spice3 restores the SPICE3f5 defaults (the trapezoidal rule, switches on the grid), which is what the ngspice oracle checks.

Install

# Python — PyPI (polars DataFrames, zero-copy numpy; module `import spice`)
pip install spice3

# JavaScript / WebAssembly — npm (runs in the browser)
npm install @strategicprojects/dune-sim

# R — tidy tibbles (CRAN submission planned)
Rscript -e 'remotes::install_github("milkway/dune", subdir = "r")'

# Rust library — crates.io (dune-netlist, dune-raw, dune-core, dune-pic)
cargo add dune-core dune-netlist

# CLI — Homebrew (macOS, Linux). homebrew-core's own `dune` is the
# OCaml build system, so the tap is part of the name
brew install milkway/tap/dune

# CLI — from source (Rust 1.88+)
git clone https://github.com/milkway/dune && cd dune && cargo build --release

The Rust crates are 0.x: the public API of dune-core may change between minor versions.

import spice

run = spice.simulate("""
step into a series rlc
V1 in 0 PULSE(0 1 0 1n 1n 1 2)
R1 in n1 60
L1 n1 out 1m
C1 out 0 1n
.tran 0.1u 40u
.end
""")
run.plots[0].df()   # polars DataFrame: time, v(in), v(out)…

Repository layout

Credits and lineage

Dune exists because of the work of others, and is derived from it:

• SPICE3f5 — © 1985–1991 The Regents of the University of California; written at the EECS Department of UC Berkeley by Thomas L. Quarles and many others, whose names are in the headers of the original files. The netlist language, the device models, the numerical methods and the analyses of Dune are translated from it. The unmodified sources are in corpus/spice3f5.
• ngspice — the maintained successor of SPICE3f5, by the ngspice team and contributors (Modified BSD licence). Dune is validated against ngspice-47, and the following are derived from its sources: BSIM3v3.3 (spicelib/devices/bsim3), the S-parameter analysis .sp (span.c, Alessio Cacciatori), the operating-point fallback chain (cktop.c, with Alan Gillespie's gmin and source stepping, and optran.c, Holger Vogt), BSIM1/BSIM2 noise (b1noi.c, b2noi.c, Paolo Nenzi), the TRNOISE/TRRANDOM sources, .measure (com_measure2.c), the switches as ngspice runs them, and every SPICE3f5 routine where Dune follows ngspice's revision (each one is named in the module comments and in corpus/KNOWN_DIFFS.md).
• BSIM3v3.3.0 — © 2004 The Regents of the University of California; developed by the UC Berkeley BSIM Research Group (JianHui Huang, Min-Chie Jeng, Mansun Chan, Gary W. Ng, Weidong Liu, Xuemei Xi).

NOTICE lists the upstream files module by module and reproduces their copyright and licence notices; it ships with every package.

Dune is an independent project: it is not affiliated with, sponsored by or endorsed by the University of California, Berkeley, the UC Berkeley BSIM Research Group or the ngspice project. The names "SPICE", "SPICE3" and "ngspice" are used only descriptively, to identify the programs whose netlist language and behaviour Dune implements. The translation was done with the assistance of AI coding tools.

License

BSD-3-Clause — © 2026 André Leite; portions derived from SPICE3f5, © 1985–1991 The Regents of the University of California, and from ngspice, © 1985–2018 The Regents of the University of California and others. See LICENSE and NOTICE.