Dimension problem for variable multiplication in ModelingToolkit.jl

Specific Domains Modelling & Simulations
1

This is what I did:

using ModelingToolkit
@parameters t
@variables a(t) b(t) c[1:2](t)

# then calculate:
(c' * [a, b]) * c

I think (c' * [a, b]) can be a scalar, so the dimension is correct.

julia> size(c' * [a, b])
()

julia> size(c)
(2,)

But it raised an error:

ERROR: MethodError: no method matching iterate(::Term{Num, Nothing})
Closest candidates are:
  iterate(::Union{LinRange, StepRangeLen}) at range.jl:664
  iterate(::Union{LinRange, StepRangeLen}, ::Int64) at range.jl:664
  iterate(::T) where T<:Union{Base.KeySet{var"#s77", var"#s76"} where {var"#s77", var"#s76"<:Dict}, Base.ValueIterator{var"#s75"} where var"#s75"<:Dict} at dict.jl:693
  ...
Stacktrace:
  [1] copyto!(dest::Vector{Any}, src::Term{Num, Nothing})
    @ Base ./abstractarray.jl:843
  [2] _collect(cont::UnitRange{Int64}, itr::Term{Num, Nothing}, #unused#::Base.HasEltype, isz::Base.HasLength)
    @ Base ./array.jl:608
  [3] collect
    @ ./array.jl:602 [inlined]
  [4] broadcastable
    @ ./broadcast.jl:682 [inlined]
  [5] broadcasted
    @ ./broadcast.jl:1312 [inlined]
  [6] broadcast(::typeof(*), ::Term{Num, Nothing}, ::Symbolics.ArrayOp{AbstractVector{Real}})
    @ Base.Broadcast ./broadcast.jl:821
  [7] materialize(bc::Base.Broadcast.Broadcasted{Symbolics.SymWrapBroadcast, Nothing, typeof(*), Tuple{Num, Symbolics.Arr{Num, 1}}})
    @ Symbolics ~/.julia/packages/Symbolics/mFWWM/src/array-lib.jl:169
  [8] broadcast_preserving_zero_d
    @ ./broadcast.jl:872 [inlined]
  [9] *(A::Num, B::Symbolics.Arr{Num, 1})
    @ Base ./arraymath.jl:52
 [10] top-level scope
    @ REPL[39]:1

I’m not sure whether I did something wrong, hope someone can help me.

2

Open an issue.

3

OK, thanks for the reminder!