# Type Stability of DifferentialEquations.jl

**URL:** https://discourse.julialang.org/t/type-stability-of-differentialequations-jl/119293
**Category:** Specific Domains
**Created:** [September 11, 2024, 6:33pm UTC](https://discourse.julialang.org/t/type-stability-of-differentialequations-jl/119293 "2024-09-11T18:33:28Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![densmojd](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/densmojd/32/206891_2.png) [@densmojd](https://discourse.julialang.org/u/densmojd)
#### Post date: [September 11, 2024, 6:33pm UTC](https://discourse.julialang.org/t/type-stability-of-differentialequations-jl/119293/1 "2024-09-11T18:33:28Z")

</div>

I’m learning how to use DifferentialEquations.jl, specifically the OrdinaryDiffEq.jl package, and making sure I do everything “type stable”. I’m seeing some issues when I use `@report_opt` from JET.jl. Here’s a MWE:

```julia
using OrdinaryDiffEq

f(u) = -u

function g()
prob = ODEProblem{false}((u, p, t) -> f(u), 1.0, (0.0, 1.0))
sol = solve(prob)
end

```

`@code_warntype g()` gives a bunch of output, but no red `Any`s. `@report_opt g()` give a bunch of output, including multiple “runtime dispatch detected”. Is this something I should worry about?