# Changing the default solving loop condition in DifferentialEquations.jl

**URL:** <https://discourse.julialang.org/t/changing-the-default-solving-loop-condition-in-differentialequations-jl/46419>\
**Category:** New to Julia\
**Tags:** package\
**Created:** [September 10, 2020, 10:08pm UTC](https://discourse.julialang.org/t/changing-the-default-solving-loop-condition-in-differentialequations-jl/46419 "2020-09-10T22:08:47Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![kapple](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kapple/32/218915_2.png) [@kapple](https://discourse.julialang.org/u/kapple)\
**Post date:** [September 10, 2020, 10:08pm UTC](https://discourse.julialang.org/t/changing-the-default-solving-loop-condition-in-differentialequations-jl/46419/1 "2020-09-10T22:08:47Z")

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Hi all!

I’m trying to implement a solver that will stop if one of the variables passes a certain value instead of time-stepping (I may thus change the title of this topic). Say e.g. `u[1] < 0 || u[1] > R` for maximum range `R`.

There are two methods I’ve been looking at, but haven’t gotten anything working (out of lack of understanding or whatnot).

Q1: The first way I figured was probably possible was to use the `isoutofdomain` input argument as `isoutofdomain = MyOutOfDomain(u, p, t)`. Is this correct? When I try it, the solver doesn’t finish (and I’ve solved without this input argument and it solves very quickly, so I’m quite confused as to how adding this would increase computation time by tonnes).

Q2: The second way I could do this is via a callback, i.e. `callback = cbRange` with `cbRange = ContinuousCallback(RangeCond, RangeAffect!)`. But I’m not quite sure how to implement `RangeAffect!` so that the solver stops.

Q3: How can I change the stopping condition from the default `tspan = (0, T)` to stopping with one of the variables (say `u[1]`) reaching certain values instead? I understand that this means it is possible for this variable potentially not reaching its stopping range values, so there would need to be some sort of implementation to catch when this happens as well.

I figured this is the most minimal way to ask my question(s), but I can expand on the context for you if you want.

Thanks in advance!

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<div class="post-metadata">

**Author:** ![klaff](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/klaff/32/7637_2.png) [@klaff](https://discourse.julialang.org/u/klaff)\
**Post date:** [September 10, 2020, 10:20pm UTC](https://discourse.julialang.org/t/changing-the-default-solving-loop-condition-in-differentialequations-jl/46419/2 "2020-09-10T22:20:23Z")

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I think you want to use a ContinuousCallback, the condition function can be something like `u[1]-desired_value` and your affect should call the `terminate!` function.

[Integrator Interface · DifferentialEquations.jl](https://diffeq.sciml.ai/stable/basics/integrator/#DiffEqBase.terminate)!

[https://diffeq.sciml.ai/stable/features/callback\_functions/#ContinuousCallback](https://diffeq.sciml.ai/stable/features/callback_functions/#ContinuousCallback)