# Solve an ODE system parameters

**URL:** <https://discourse.julialang.org/t/solve-an-ode-system-parameters/34498>\
**Category:** New to Julia\
**Tags:** diffeq\
**Created:** [February 12, 2020, 1:04am UTC](https://discourse.julialang.org/t/solve-an-ode-system-parameters/34498 "2020-02-12T01:04:12Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Lecalvaire](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@Lecalvaire](https://discourse.julialang.org/u/Lecalvaire)\
**Post date:** [February 12, 2020, 1:04am UTC](https://discourse.julialang.org/t/solve-an-ode-system-parameters/34498/1 "2020-02-12T01:04:12Z")

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Hello,  
First of all, I must say that it’s (almost) my first use of the language; I usually use Matlab or Mathematica but for this special purpose I need an open source software, so I give a chance to Julia.  
Here is my problem:  
I have a coupled system of ODE’s which have the following form  
 ![CodeCogsEqn](https://global.discourse-cdn.com/julialang/original/3X/9/7/97b00ab299e2a2670616ba46c7544d2d1a873ce4.png)  
where a,M,E,L,Q are parameters. The boundary conditions are at infinity for each of the variables (in fact, I have computed the serie at infinity for them).  
Other informations: a,M,E are fixed and will never change (don’t worry about them) but I would like to be able to varry L and Q easily and continuously if possible since they are the prameters for a surface I’d like to plot afterwards.

Is there any examples of similar codes so that I can understand the syntax ?  
The right hand sides are quite simple functions involving trigonometric and powers, should I create subfunctions for a cleaner code or will it slow down the procedure ?  
Any other advice ? (specific arguments to the functions…)

Thank you very much !

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<div class="post-metadata">

**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [February 12, 2020, 1:51am UTC](https://discourse.julialang.org/t/solve-an-ode-system-parameters/34498/2 "2020-02-12T01:51:15Z")

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> [@Lecalvaire](#):
>
> The boundary conditions are at infinity for each of the variables (in fact, I have computed the serie at infinity for them)

If you’re looking for the steady states of an IVP, use a `SteadyStateProblem`:

[https://docs.juliadiffeq.org/latest/types/steady\_state\_types/](https://docs.juliadiffeq.org/latest/types/steady_state_types/)  
[https://docs.juliadiffeq.org/latest/solvers/steady\_state\_solve/](https://docs.juliadiffeq.org/latest/solvers/steady_state_solve/)

> [@Lecalvaire](#):
>
> Other informations: a,M,Ea,M,E are fixed and will never change (don’t worry about them) but I would like to be able to varry LL and QQ easily and continuously if possible since they are the prameters for a surface I’d like to plot afterwards.

Enclose those 3, and then make the other two parameters. Then use Interact.jl to turn them into sliders:

> **[GitHub - JuliaGizmos/Interact.jl: Interactive widgets to play with your Julia...](https://github.com/JuliaGizmos/Interact.jl)**
>
> Interactive widgets to play with your Julia code. Contribute to JuliaGizmos/Interact.jl development by creating an account on GitHub.