Project Rat - Your magnet's best friend

Start your Rat project today with the open source library

Rat is completely modular and because it is open source it can be easily integrated into your own projects. It includes a 3D mesher, a database with material properties, the MLFMM algorithm and a library that eases the modeling of magnets and magnets systems. In addition, there is a library specially made for Canted Cosine Theta magnets, which are often applied in medical accelerators for example.

It can be difficult to get started with Rat Library since it is written in C++ and is most easily run on Linux-based operating systems. Therefore, we at Little Beast Engineering have also developed a Graphical User Interface (GUI). This GUI provides easy access to the Rat Library. It allows the user to build a magnet, and calculate its electromagnetic properties within minutes from the installation! And it's available on Windows, and some Linux distributions.

The Rat Library - Dedicated tools for magnet engineers

Published on GitLab under the MIT License

Rat Common

Rat Common

This is Rat's toolbox. It contains some general use classes like the logger and the serializer. Rat MLFMM, Rat Distmesh-cpp and Rat Materials all depend on this library.


This repository hosts a heavily parallelized and vectorized open source Multi-Level Fast Multipole Method (MLFMM) capable of calculating the magnetic field and vector potential.

Rat Distmesh-cpp

In this repository you find a C++ version of the famous distmesh mesher originally written in Matlab by P.-O. Persson available here.

Rat Materials

An open source material database in C++, which Rat uses for some of the calculations. Everyone is welcome to contribute data!

Rat Models

This library simplifies building coil geometries and electromagnetic calculations in 3D, and it includes classes for magnetic field calculations.

Rat Template

A quick start template for a C++ API that includes the Rat Library. Fork it and get started straight away!