# Incidence matrix from ModelingToolkit.jl

**URL:** https://discourse.julialang.org/t/incidence-matrix-from-modelingtoolkit-jl/111626
**Category:** Modelling & Simulations
**Created:** [March 14, 2024, 3:56pm UTC](https://discourse.julialang.org/t/incidence-matrix-from-modelingtoolkit-jl/111626 "2024-03-14T15:56:35Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![hhindley](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hhindley/32/207751_2.png) [@hhindley](https://discourse.julialang.org/u/hhindley)
#### Post date: [March 14, 2024, 3:56pm UTC](https://discourse.julialang.org/t/incidence-matrix-from-modelingtoolkit-jl/111626/1 "2024-03-14T15:56:35Z")

</div>

Hi, I’ve just started using ModelingToolkit properly and am looking at doing some hybrid stochastic modelling. For my framework I need the stoichiometric matrix and reaction propensities. In the @mtkbuild output there is an incidence matrix shown.

So my question: is there a way to save this incidence matrix or access it after the model has been built?

It seems silly to have to completely redefine my model to build a stoichiometric matrix with reaction propensities when it seems like ModelingToolkit can access this kind of information.

Apologies if I’m being naive with the capabilities of this package…  
Thanks!