# Is there a way to use non-constant mass matrix depended from u?

**URL:** <https://discourse.julialang.org/t/is-there-a-way-to-use-non-constant-mass-matrix-depended-from-u/121787>\
**Category:** New to Julia\
**Tags:** diffeq, differentialequation\
**Created:** [October 26, 2024, 1:32pm UTC](https://discourse.julialang.org/t/is-there-a-way-to-use-non-constant-mass-matrix-depended-from-u/121787 "2024-10-26T13:32:29Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![garazha-ilya](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/garazha-ilya/32/214384_2.png) [@garazha-ilya](https://discourse.julialang.org/u/garazha-ilya)\
**Post date:** [October 26, 2024, 1:32pm UTC](https://discourse.julialang.org/t/is-there-a-way-to-use-non-constant-mass-matrix-depended-from-u/121787/1 "2024-10-26T13:32:29Z")

</div>

Hello!  
The DifferentialEquations.jl documentation says that:

> Non-constant mass matrices are not directly supported: users are advised to transform their problem through substitution to a DAE with constant mass matrices.

Am I right that there is no automated solution for write the system the way it is?

As a sample, I was guided by Matlab example " Solve Equations of Motion for Baton Thrown into Air" (sorry I can’t add link) where non-constant mass matrix M defined directly.

Is there any plans to add the possibility of using non-constant mass matrix it in the near future?

Thank you