Milan Rother

I build the simulation stack for electronics: fields, circuits, systems. Custom solvers and engineering tools for client teams, built and integrated end to end.

What I do

Consulting: custom solvers and engineering tools, built and integrated end to end. Scoped into weekly sprints and multi-week projects.

Products & licensing: FastSim, SANE, and RapidMoM are source-available, free for academia, and commercially licensed with support and integration.

About: simulation engineer, open-source author of PathSim.

Who am I

I build simulation tools and infrastructure and solve numerical modeling problems for engineering teams.

Long ago during my studies I was already building small numerical side projects. A symbolic circuit analysis tool, an eigenmode solver for the Schrödinger equation, a CUDA-accelerated 2D FDTD solver, a MIMO vector fitting implementation, and so on. I even wrote a 120-page LaTeX manuscript on linear system theory during the summer of 2021 to help out a friend.

During my master's I dipped my toes into the RFIC EDA world and worked on compact modeling and layout generation of RFIC passives (inductors, transformers, baluns...). This has now become RapidPassives, an open-source library.

At the beginning of my PhD (early 2023) I diverged from the circuit path to the more general system level, where you have signal flow diagrams and ODEs instead of Maxwell and KVL/KCL. During that time PathSim started as a side project. Initially just an analog computer emulator, it evolved into a fully fledged continuous and discrete (hybrid, we have events!) system modeling and simulation framework. I announced it in March 2025 as an open alternative to Simulink, and a modern take on system modeling in general. Clean API, mutability from the get-go, robust solvers (stiffness, algebraic loops, no problem). Today (mid 2026) we are at roughly 400 stars on GitHub and have many users and collaborators worldwide, some of them prominent figures such as the MIT Plasma Science and Fusion Center, scikit-rf, and JSBSim developers.

Now I'm making the full roundtrip back through circuits and fields, bringing it all together into one vertically integrated stack: EM solvers (RapidFEM, RapidMoM), a symbolic circuit engine (SANE), and system-level simulation (PathSim, FastSim). One architecture: SSA-style compute graphs at the heart of the engines, Rust cores, Python APIs, browser interfaces. The commercial EDA world splits these levels across vendors and decades of legacy. I think one coherent, modern stack can do better.

Those who have talked to me know that I can't stop talking about numerics, modeling, and simulation principles and ideas.

I work as a freelancer and license my tools commercially, free for academia. If you have something you want my take on, or need some ideas and even implementation, don't hesitate to reach out.

The Stack

One vertically integrated simulation stack for electronics: from electromagnetic fields to circuits to systems. Open source where it builds trust, source-available and commercially licensed where it creates value. Free for academia.

Systems

PathSim: pure-Python system simulation framework, MIT open source, JOSS-published. FastSim: drop-in Rust replacement with 191x median per-step speedup, JIT, autodiff, FMI 3.0, C99 code generation. PathView: browser-based visual model editor.

Circuits

SANE: Symbolic Analog Network Engine. Symbolic and numeric circuit analysis: DC, transient, AC, poles/zeros, noise, harmonic balance, exact sensitivities. SPICE and Verilog-A frontends. Validated against ngspice and Xyce.

Fields

RapidMoM: 2.5D Method-of-Moments solver for planar RF passives on layered substrates. RapidFEM: Maxwell FEM solver in Rust with frequency-domain and time-domain backends. RapidPassives: browser-based RFIC passive layout generation.

Foundations

RSLAB: sparse direct solver in pure Rust. RapidMesh: mesh generator for electromagnetic FEM and MoM.

Other Projects

Side quests: tools I built because I wanted them to exist.

  • PySimHub: An open community catalog bridging Python's scattered simulation communities. An awesome list that's also awesome to use.
  • SciData: A node-based environment for scientific data analysis. Drop a CSV, chain pandas, scipy, statsmodels and plotly blocks; the pipeline is a declarative graph that compiles to plain Python.
  • ThesisOS: A local-first literature manager for researchers. Ingest PDFs, search them semantically, and trace citations across your library.
  • WhatsMyTraffic: Self-hosted web analytics with a form backend and passwordless auth. A Docker stack (Umami, Postgres, a SvelteKit dashboard behind Caddy) on a VPS.
  • falllow: A distributed compute pool for tests and builds. Enrol the machines you already own; work lands on whichever is free, runs in a container with reserved threads and memory, and reports back the command's own exit code.

Get in Touch

Have a project in mind or want to discuss your simulation challenges?

Contact: info@milanrother.com