Interpolating solution after `strip_solution` not working

[jClugstor]

Describe the bug 🐞
After using strip_solution on an ODESolution, interpolation, e.g. stripped_sol(0.5) does not work.

The issue is at line 230 of ode_solutions.jl where the functor for AbstractODESolution is defined:

function (sol::AbstractODESolution)(t::Number, ::Type{deriv}, idxs::Nothing,
        continuity) where {deriv}
    sol.interp(t, idxs, deriv, sol.prob.p, continuity)
end

The interp takes sol.prob.p as input, but when a solution is stripped, prob is nothing.

Expected behavior
When doing stripped_sol(0.5) I expect to get an interpolated value at the time 0.5.
Minimal Reproducible Example 👇

using OrdinaryDiffEq
f(u, p, t) = 1.01 * u
u0 = 1 / 2
tspan = (0.0, 1.0)
prob = ODEProblem(f, u0, tspan)
sol = solve(prob, Tsit5(), reltol=1e-8, abstol=1e-8)

stripped_sol = SciMLBase.strip_solution(sol)

stripped_sol(0.4)

Error & Stacktrace ⚠️

ERROR: type Nothing has no field p
Stacktrace:
 [1] getproperty(x::Nothing, f::Symbol)
   @ Base ./Base.jl:37
 [2] (::ODESolution{…})(t::Float64, ::Type{…}, idxs::Nothing, continuity::Symbol)
   @ SciMLBase ~/.julia/packages/SciMLBase/j8jQg/src/solutions/ode_solutions.jl:232
 [3] (::ODESolution{…})(t::Float64, ::Type{…}; idxs::Nothing, continuity::Symbol)
   @ SciMLBase ~/.julia/packages/SciMLBase/j8jQg/src/solutions/ode_solutions.jl:220
 [4] (::ODESolution{…})(t::Float64, ::Type{…})
   @ SciMLBase ~/.julia/packages/SciMLBase/j8jQg/src/solutions/ode_solutions.jl:215
 [5] top-level scope
   @ ~/Documents/Work/dev/ODiffEq/SerializationTest.jl:10
Some type information was truncated. Use `show(err)` to see complete types.

Environment (please complete the following information):

• Output of using Pkg; Pkg.status()

Status `~/Documents/Work/dev/ODiffEq/Project.toml`
⌃ [033835bb] JLD2 v0.5.1
  [1dea7af3] OrdinaryDiffEq v6.89.0
  [bbf590c4] OrdinaryDiffEqCore v1.6.0
  [0bca4576] SciMLBase v2.53.1

• Output of using Pkg; Pkg.status(; mode = PKGMODE_MANIFEST)

Status `~/Documents/Work/dev/ODiffEq/Manifest.toml`
⌃ [47edcb42] ADTypes v1.7.1
  [7d9f7c33] Accessors v0.1.38
  [79e6a3ab] Adapt v4.0.4
  [ec485272] ArnoldiMethod v0.4.0
  [4fba245c] ArrayInterface v7.16.0
  [4c555306] ArrayLayouts v1.10.3
  [62783981] BitTwiddlingConvenienceFunctions v0.1.6
  [2a0fbf3d] CPUSummary v0.2.6
⌃ [d360d2e6] ChainRulesCore v1.24.0
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  [38540f10] CommonSolve v0.2.4
  [bbf7d656] CommonSubexpressions v0.3.1
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⌅ [6b7a57c9] Expronicon v0.8.5
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  [3e5b6fbb] HostCPUFeatures v0.1.17
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  [82899510] IteratorInterfaceExtensions v1.0.0
⌃ [033835bb] JLD2 v0.5.1
  [692b3bcd] JLLWrappers v1.6.0
  [ef3ab10e] KLU v0.6.0
  [ba0b0d4f] Krylov v0.9.6
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  [d8e11817] MLStyle v0.4.17
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  [bb5d69b7] MaybeInplace v0.1.4
  [46d2c3a1] MuladdMacro v0.2.4
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  [77ba4419] NaNMath v1.0.2
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  [6fe1bfb0] OffsetArrays v1.14.1
  [bac558e1] OrderedCollections v1.6.3
  [1dea7af3] OrdinaryDiffEq v6.89.0
  [89bda076] OrdinaryDiffEqAdamsBashforthMoulton v1.1.0
  [6ad6398a] OrdinaryDiffEqBDF v1.1.2
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  [101fe9f7] OrdinaryDiffEqFeagin v1.1.0
  [d3585ca7] OrdinaryDiffEqFunctionMap v1.1.1
  [d28bc4f8] OrdinaryDiffEqHighOrderRK v1.1.0
  [9f002381] OrdinaryDiffEqIMEXMultistep v1.1.0
  [521117fe] OrdinaryDiffEqLinear v1.1.0
  [1344f307] OrdinaryDiffEqLowOrderRK v1.2.0
  [b0944070] OrdinaryDiffEqLowStorageRK v1.2.1
  [127b3ac7] OrdinaryDiffEqNonlinearSolve v1.2.1
  [c9986a66] OrdinaryDiffEqNordsieck v1.1.0
  [5dd0a6cf] OrdinaryDiffEqPDIRK v1.1.0
  [5b33eab2] OrdinaryDiffEqPRK v1.1.0
  [04162be5] OrdinaryDiffEqQPRK v1.1.0
  [af6ede74] OrdinaryDiffEqRKN v1.1.0
  [43230ef6] OrdinaryDiffEqRosenbrock v1.2.0
  [2d112036] OrdinaryDiffEqSDIRK v1.1.0
  [669c94d9] OrdinaryDiffEqSSPRK v1.2.0
  [e3e12d00] OrdinaryDiffEqStabilizedIRK v1.1.0
  [358294b1] OrdinaryDiffEqStabilizedRK v1.1.0
  [fa646aed] OrdinaryDiffEqSymplecticRK v1.1.0
  [b1df2697] OrdinaryDiffEqTsit5 v1.1.0
  [79d7bb75] OrdinaryDiffEqVerner v1.1.1
  [65ce6f38] PackageExtensionCompat v1.0.2
  [d96e819e] Parameters v0.12.3
  [f517fe37] Polyester v0.7.16
  [1d0040c9] PolyesterWeave v0.2.2
  [d236fae5] PreallocationTools v0.4.24
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  [21216c6a] Preferences v1.4.3
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  [7e49a35a] RuntimeGeneratedFunctions v0.5.13
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  [c0aeaf25] SciMLOperators v0.3.10
  [53ae85a6] SciMLStructures v1.5.0
  [efcf1570] Setfield v1.1.1
⌃ [727e6d20] SimpleNonlinearSolve v1.12.0
  [699a6c99] SimpleTraits v0.9.4
  [ce78b400] SimpleUnPack v1.1.0
  [47a9eef4] SparseDiffTools v2.20.0
  [0a514795] SparseMatrixColorings v0.4.0
  [e56a9233] Sparspak v0.3.9
  [276daf66] SpecialFunctions v2.4.0
  [aedffcd0] Static v1.1.1
  [0d7ed370] StaticArrayInterface v1.8.0
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  [2efcf032] SymbolicIndexingInterface v0.3.30
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  [d5829a12] TriangularSolve v0.2.1
  [410a4b4d] Tricks v0.1.9
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  [3a884ed6] UnPack v1.0.2
  [3d5dd08c] VectorizationBase v0.21.70
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• Output of versioninfo()

Julia Version 1.10.4
Commit 48d4fd48430 (2024-06-04 10:41 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 16 × AMD Ryzen 7 6800U with Radeon Graphics
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-15.0.7 (ORCJIT, znver3)
Threads: 16 default, 0 interactive, 8 GC (on 16 virtual cores)
Environment:
  JULIA_EDITOR = code

[jClugstor]

@ChrisRackauckas
I can't make prob.f in to nothing, the inner constructor doesn't allow it.

I can define a singleton

struct ODENullFunction <: SciMLBase.AbstractODEFunction{false} end

or something similar and make a new ODEProblem with it as prob.f. I tested that and it does let interpolation work. Sound ok?

[ChrisRackauckas]

Why not just make it (;p=nothing)?

[jClugstor]

Where do you mean?

[ChrisRackauckas]

@set! prob.f = (;p=nothing)

[jClugstor]

Ohh

[jClugstor]

f needs to be an AbstractODEFunction, the inner constructor for ODEProblem doesn't let it be anything else.

[ChrisRackauckas]

okay then just make a singleton with a getproperty

[jClugstor]

Actually, @set sol.prob = (; p = nothing) does work without the need for a singleton, and makes interpolation work. #790