# Missing from the variable map error

**URL:** <https://discourse.julialang.org/t/missing-from-the-variable-map-error/63172>\
**Category:** General Usage\
**Tags:** question, package, modelingtoolkit\
**Created:** [June 19, 2021, 6:13am UTC](https://discourse.julialang.org/t/missing-from-the-variable-map-error/63172 "2021-06-19T06:13:52Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![cadojo](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/cadojo/32/25328_2.png) [@cadojo](https://discourse.julialang.org/u/cadojo)\
**Post date:** [June 19, 2021, 6:13am UTC](https://discourse.julialang.org/t/missing-from-the-variable-map-error/63172/1 "2021-06-19T06:13:52Z")

</div>

I’m trying to construct an `ODEProblem` from a `ODESystem` with the following code. I can’t seem to debug this error.

```julia
using ModelingToolkit
using LinearAlgebra
using StaticArrays

@parameters t μ 
@variables x(t) y(t) z(t) ẋ(t) ẏ(t) ż(t)
δ = Differential(t)
r = @SVector [x,y,z]
v = @SVector [ẋ,ẏ,ż]

eqs = vcat(
    δ.(r) .~ v,
    δ.(v) .~ -μ .* (r ./ norm(r)^3)
)

@named R2BP = ODESystem(eqs, t, vcat(r,v), [μ])

x₀ = Dict(
    R2BP.x => 1e4,
    R2BP.y => 0.0,
    R2BP.z => 1e4,
    R2BP.ẋ => 1e3,
    R2BP.ẏ => 0.0,
    R2BP.ż => -2e3
)

ts = (0.0, 1e4)

μ = Dict(R2BP.μ => 5e6)

ODEProblem(R2BP, x₀, ts, μ)

```

```julia
ERROR: ArgumentError: Term{Real, Nothing}[x(t), y(t), z(t), ẋ(t), ẏ(t), ż(t)] are missing from the variable map.
Stacktrace:
  [1] throw_missingvars(vars::Vector{Term{Real, Nothing}})
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/MuQfD/src/variables.jl:67
  [2] _varmap_to_vars(varmap::Dict{Term{Real, Nothing}, Float64}, varlist::Vector{Term{Real, Nothing}}; defaults::Dict{Any, Any}, check::Bool, toterm::typeof(Symbolics.diff2term))
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/MuQfD/src/variables.jl:59
  [3] varmap_to_vars(varmap::Dict{Term{Real, Nothing}, Float64}, varlist::Vector{Term{Real, Nothing}}; defaults::Dict{Any, Any}, check::Bool, toterm::Function)
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/MuQfD/src/variables.jl:34
  [4] process_DEProblem(constructor::Type, sys::ODESystem, u0map::Dict{Term{Real, Nothing}, Float64}, parammap::Dict{Sym{Real, Base.ImmutableDict{DataType, Any}}, Float64}; implicit_dae::Bool, du0map::Nothing, version::Nothing, tgrad::Bool, jac::Bool, checkbounds::Bool, sparse::Bool, simplify::Bool, linenumbers::Bool, parallel::Symbolics.SerialForm, eval_expression::Bool, kwargs::Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/MuQfD/src/systems/diffeqs/abstractodesystem.jl:433
  [5] process_DEProblem
    @ ~/.julia/packages/ModelingToolkit/MuQfD/src/systems/diffeqs/abstractodesystem.jl:409 [inlined]
  [6] (ODEProblem{true, tType, isinplace, P, F, K, PT} where {tType, isinplace, P, F, K, PT})(sys::ODESystem, u0map::Dict{Term{Real, Nothing}, Float64}, tspan::Tuple{Float64, Float64}, parammap::Dict{Sym{Real, Base.ImmutableDict{DataType, Any}}, Float64}; kwargs::Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/MuQfD/src/systems/diffeqs/abstractodesystem.jl:522
  [7] (ODEProblem{true, tType, isinplace, P, F, K, PT} where {tType, isinplace, P, F, K, PT})(sys::ODESystem, u0map::Dict{Term{Real, Nothing}, Float64}, tspan::Tuple{Float64, Float64}, parammap::Dict{Sym{Real, Base.ImmutableDict{DataType, Any}}, Float64})
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/MuQfD/src/systems/diffeqs/abstractodesystem.jl:522
  [8] ODEProblem(::ODESystem, ::Dict{Term{Real, Nothing}, Float64}, ::Vararg{Any, N} where N; kwargs::Base.Iterators.Pairs{Union{}, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/MuQfD/src/systems/diffeqs/abstractodesystem.jl:501
  [9] ODEProblem(::ODESystem, ::Dict{Term{Real, Nothing}, Float64}, ::Vararg{Any, N} where N)
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/MuQfD/src/systems/diffeqs/abstractodesystem.jl:501
 [10] top-level scope
    @ REPL[6]:1

```

---

<div class="post-metadata">

**Author:** ![cadojo](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/cadojo/32/25328_2.png) [@cadojo](https://discourse.julialang.org/u/cadojo)\
**Post date:** [June 19, 2021, 6:22am UTC](https://discourse.julialang.org/t/missing-from-the-variable-map-error/63172/2 "2021-06-19T06:22:23Z")

</div>

Update. This code works if I remove the `R2BP.` in front of each state variable and parameter. But then how can I create an `ODEProblem` from the `ODESystem` if the `ODESystem` is defined in another package?

This is described in [this issue](https://github.com/SciML/ModelingToolkit.jl/issues/1049) and others.

---

<div class="post-metadata">

**Author:** ![jonniedie](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jonniedie/32/12842_2.png) [@jonniedie](https://discourse.julialang.org/u/jonniedie)\
**Post date:** [June 22, 2021, 3:05am UTC](https://discourse.julialang.org/t/missing-from-the-variable-map-error/63172/3 "2021-06-22T03:05:49Z")

</div>

You can use the `@nonamespace` macro in front of your initial condition and parameter declarations.

```julia
@nonamespace x₀ = Dict(
    R2BP.x => 1e4,
    R2BP.y => 0.0,
    R2BP.z => 1e4,
    R2BP.ẋ => 1e3,
    R2BP.ẏ => 0.0,
    R2BP.ż => -2e3
)

@nonamespace μ = Dict(R2BP.μ => 5e6)

```

---

<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:** [June 22, 2021, 5:54am UTC](https://discourse.julialang.org/t/missing-from-the-variable-map-error/63172/4 "2021-06-22T05:54:19Z")

</div>

Yup this is the right answer for now. But given how non-intuitive it is, there’s a breaking change coming to switch the assumption of implicit namespacing. Just noting that it’s coming rather soon.

---

<div class="post-metadata">

**Author:** ![TheLateKronos](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/thelatekronos/32/12824_2.png) [@TheLateKronos](https://discourse.julialang.org/u/TheLateKronos)\
**Post date:** [March 8, 2023, 7:57am UTC](https://discourse.julialang.org/t/missing-from-the-variable-map-error/63172/5 "2023-03-08T07:57:53Z")

</div>

I know I have read the proper way to do this now. It should probably be linked here.