https://github.com/modiasim/modiabase.jl

Core algorithms for equation-based modeling
https://github.com/modiasim/modiabase.jl

Last synced: 8 months ago
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Core algorithms for equation-based modeling

• Host: GitHub
• URL: https://github.com/modiasim/modiabase.jl
• Owner: ModiaSim
• License: mit
• Created: 2021-02-03T16:15:50.000Z (over 5 years ago)
• Default Branch: main
• Last Pushed: 2024-03-10T07:39:07.000Z (over 2 years ago)
• Last Synced: 2025-10-21T12:44:39.435Z (8 months ago)
• Language: Julia
• Size: 672 KB
• Stars: 10
• Watchers: 7
• Forks: 6
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.md

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README

          
# ModiaBase

 

[![Stable](https://img.shields.io/badge/docs-stable-blue.svg)](https://modiasim.github.io/ModiaBase.jl/stable/)

[![The MIT License](https://img.shields.io/badge/license-MIT-brightgreen.svg?style=flat-square)](https://github.com/ModiaSim/ModiaBase.jl/blob/master/LICENSE.md)

ModiaBase is part of [ModiaSim](https://modiasim.github.io/docs/). It is usually used via [Modia](https://github.com/ModiaSim/Modia.jl).

The [ModiaBase documentation](https://modiasim.github.io/ModiaBase.jl/stable/) provides details of the algorithms and how to use them.

ModiaBase provides basic algorithms and functionality that is needed for

equation-based modeling to transform a (potentially high-index) Differential-Algebraic Equation system (DAE),

to an Ordinary Differential Equation system in state space form (ODE).

It is used by [Modia](https://github.com/ModiaSim/Modia.jl),

but can also be utilized in another context. Especially the following functionality is provided:

- Simplify linear Integer equations (many equations of object-oriented models are linear Integer equations and can be pre-processed exactly)

  - to remove alias variables and equations,

  - to remove redundant equations,

  - to provide definite values for variables that can have arbitrary values if this makes sense,

  - to make state constraints structurally visible.

  

- Find a variable assignment of an equation system, in order

  to transform the equation system in a directed graph that can be further

  processed.

  

- Find the strong components in a directed graph (with the algorithm of Tarjan)

  to determine algebraic equation systems that must be solved together.

- Sort an equation system (= transform to Block Lower Triangular form), 

  to determine the order in which the equations have to be evaluated.

  

- Reduce the dimension of algebraic equation systems by tearing.

 

- Find equations that need to be differentiated one or more times (with the algorithm of Pantelides)

  in order that the DAE can be transformed to an ODE.

- Analytically differentiate the found equations.

- Statically select ODE states and transform to ODE form

  (hereby identifying linear equation systems that must be solved during simulation).

  

## Installation

 

Typically, a user installs [Modia](https://github.com/ModiaSim/Modia.jl) and does not need

to install ModiaBase separately. If needed, ModiaBase is installed with (Julia 1.7 is required):

```julia

julia> ]add ModiaBase

```

## Main Developers

- [Hilding Elmqvist](mailto:Hilding.Elmqvist@Mogram.net), [Mogram](http://www.mogram.net/).

- [Martin Otter](https://rmc.dlr.de/sr/en/staff/martin.otter/),

  [DLR - Institute of System Dynamics and Control](https://www.dlr.de/sr/en).

  

License: MIT (expat)