# Solving Delay differential equation with variable delay

**URL:** https://discourse.julialang.org/t/solving-delay-differential-equation-with-variable-delay/113137
**Category:** New to Julia
**Created:** [April 18, 2024, 10:20am UTC](https://discourse.julialang.org/t/solving-delay-differential-equation-with-variable-delay/113137 "2024-04-18T10:20:54Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![Lucas\_Sarrazin](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/lucas_sarrazin/32/208577_2.png) [@Lucas\_Sarrazin](https://discourse.julialang.org/u/Lucas_Sarrazin)
#### Post date: [April 18, 2024, 10:20am UTC](https://discourse.julialang.org/t/solving-delay-differential-equation-with-variable-delay/113137/1 "2024-04-18T10:20:54Z")

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Hi everyone,  
I am very new to Julia and I want to wrote a code for solving a delay differential equation with variable delay of the form :  
x’(t) = 1 + y(t)  
y’(t) = y(t - tau(t)) + y0  
with initial conditions xi = 0 and yi = y0.  
where tau is the delay and can be of the form :  
tau(t) = 1 + arcsin(sin(t)).

basically I don’t really know where to start …

Thanks for the Help

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### 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: [April 18, 2024, 12:23pm UTC](https://discourse.julialang.org/t/solving-delay-differential-equation-with-variable-delay/113137/2 "2024-04-18T12:23:42Z")

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See:

> **[Delay Differential Equations · DifferentialEquations.jl](https://docs.sciml.ai/DiffEqDocs/stable/tutorials/dde_example/#Delay-Differential-Equations)**
>
> Documentation for DifferentialEquations.jl.