Array variable units

[aml5600]

Describe the bug 🐞

It appears that while units may be given to array variables, those units cannot then be "gotten". This is leading to further issues when trying to use the variables.

Expected behavior

For a symbolic array (versus an array of variables?) return the correct unit type.

Minimal Reproducible Example 👇

using ModelingToolkit, DynamicQuantities
@variables x(t)[1:3], [unit = u"m"]
ModelingToolkit.get_unit(x)

Error & Stacktrace ⚠️

julia> ModelingToolkit.get_unit(x)
ERROR: There was an error processing arrayop expression 1.0 m.
Dimension of output index i in (i,) could not be inferred
Stacktrace:
  [1] error(s::String)
    @ Base ./error.jl:35
  [2] (::Symbolics.var"#99#102"{Tuple{…}, Quantity{…}, Dict{…}, Dict{…}})(i::SymbolicUtils.BasicSymbolic{Int64})
    @ Symbolics ~/.julia/packages/Symbolics/qoXk1/src/arrays.jl:222
  [3] map
    @ ./tuple.jl:291 [inlined]
  [4] make_shape(output_idx::Tuple{…}, expr::Quantity{…}, ranges::Dict{…})
    @ Symbolics ~/.julia/packages/Symbolics/qoXk1/src/arrays.jl:216
  [5] Symbolics.ArrayOp(T::Type, output_idx::Tuple{…}, expr::Quantity{…}, reduce::Function, term::SymbolicUtils.BasicSymbolic{…}, ranges::Dict{…}; metadata::Nothing)
    @ Symbolics ~/.julia/packages/Symbolics/qoXk1/src/arrays.jl:53
  [6] ArrayOp
    @ ~/.julia/packages/Symbolics/qoXk1/src/arrays.jl:52 [inlined]
  [7] Symbolics.ArrayOp(T::Type, output_idx::Tuple{…}, expr::Quantity{…}, reduce::Function, term::SymbolicUtils.BasicSymbolic{…})
    @ Symbolics ~/.julia/packages/Symbolics/qoXk1/src/arrays.jl:52
  [8] _map(::Function, ::SymbolicUtils.BasicSymbolic{Vector{Real}})
    @ Symbolics ~/.julia/packages/Symbolics/qoXk1/src/array-lib.jl:340
  [9] macro expansion
    @ ~/.julia/packages/Symbolics/qoXk1/src/array-lib.jl:326 [inlined]
 [10] var"Base.map_4228762831532280247"(nothing::Nothing, f::Function, x::SymbolicUtils.BasicSymbolic{Vector{Real}})
    @ Symbolics ~/.julia/packages/Symbolics/qoXk1/src/wrapper-types.jl:143
 [11] map(f::Function, x::Symbolics.Arr{Num, 1})
    @ Symbolics ~/.julia/packages/Symbolics/qoXk1/src/wrapper-types.jl:152
 [12] get_unit(x::Symbolics.Arr{Num, 1})
    @ ModelingToolkit ~/workspace/ModelingToolkit.jl/src/systems/unit_check.jl:70
 [13] top-level scope
    @ REPL[4]:1
Some type information was truncated. Use `show(err)` to see complete types.

Environment (please complete the following information):

• Output of using Pkg; Pkg.status()

(ModelingToolkit) pkg> st
Project ModelingToolkit v9.36.0
Status `~/workspace/ModelingToolkit.jl/Project.toml`
  [1520ce14] AbstractTrees v0.4.5
  [4fba245c] ArrayInterface v7.15.0
  [8e7c35d0] BlockArrays v1.1.0
  [861a8166] Combinatorics v1.0.2
  [34da2185] Compat v4.16.0
  [187b0558] ConstructionBase v1.5.7
  [864edb3b] DataStructures v0.18.20
  [2b5f629d] DiffEqBase v6.154.0
  [459566f4] DiffEqCallbacks v3.8.0
  [77a26b50] DiffEqNoiseProcess v5.23.0
  [b552c78f] DiffRules v1.15.1
  [31c24e10] Distributions v0.25.110
  [ffbed154] DocStringExtensions v0.9.3
  [5b8099bc] DomainSets v0.7.14
⌅ [06fc5a27] DynamicQuantities v0.13.2
  [e2ba6199] ExprTools v0.1.10
⌅ [6b7a57c9] Expronicon v0.8.5
  [64ca27bc] FindFirstFunctions v1.3.0
  [f6369f11] ForwardDiff v0.10.36
  [77dc65aa] FunctionWrappersWrappers v0.1.3
  [86223c79] Graphs v1.11.2
  [98e50ef6] JuliaFormatter v1.0.59
  [ccbc3e58] JumpProcesses v9.13.3
  [23fbe1c1] Latexify v0.16.5
  [d8e11817] MLStyle v0.4.17
  [77ba4419] NaNMath v1.0.2
  [8913a72c] NonlinearSolve v3.14.0
  [bac558e1] OrderedCollections v1.6.3
  [aea7be01] PrecompileTools v1.2.1
  [731186ca] RecursiveArrayTools v3.27.0
  [189a3867] Reexport v1.2.2
  [7e49a35a] RuntimeGeneratedFunctions v0.5.13
  [0bca4576] SciMLBase v2.50.1
  [53ae85a6] SciMLStructures v1.4.2
  [efcf1570] Setfield v1.1.1
  [727e6d20] SimpleNonlinearSolve v1.12.0
  [276daf66] SpecialFunctions v2.4.0
  [90137ffa] StaticArrays v1.9.7
  [2efcf032] SymbolicIndexingInterface v0.3.28
  [d1185830] SymbolicUtils v3.4.0
  [0c5d862f] Symbolics v6.3.0
  [5c2747f8] URIs v1.5.1
  [3a884ed6] UnPack v1.0.2
  [1986cc42] Unitful v1.21.0
  [8ba89e20] Distributed
  [b77e0a4c] InteractiveUtils
  [8f399da3] Libdl
  [37e2e46d] LinearAlgebra
  [9e88b42a] Serialization
  [2f01184e] SparseArrays v1.10.0

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

• Output of versioninfo()

julia> versioninfo()
Julia Version 1.10.4
Commit 48d4fd48430 (2024-06-04 10:41 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: macOS (arm64-apple-darwin22.4.0)
  CPU: 8 × Apple M1 Pro
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-15.0.7 (ORCJIT, apple-m1)
Threads: 8 default, 0 interactive, 4 GC (on 6 virtual cores)
Environment:
  JULIA_EDITOR = code
  JULIA_NUM_THREADS = 8

Additional context

Add any other context about the problem here.

[aml5600]

ModelingToolkit.get_unit(ModelingToolkit.unwrap(x)) returns the correct result, though. So if this is the desired fix, I can make a PR. Thanks!

[ChrisRackauckas]

That is correct. I guess Num on Arr was just missing a dispatch.