I am having a hard time with a NL model that I am creating. My model uses matrices and therefore my variable and constraints are arrays.

I want to create an array of constraints that includes some calculations with my variable S but I get an error message that doesn’t help me much.

I provide a MWE with some comments that I hope may be useful. I use JuMP v0.21.4 and Julia v1.4.2.

```
#model size
(K,T,E)=(6,2,2)
m = Model(Ipopt.Optimizer)
#Defining variables
@variable(m, S[1:K*T,1,1:E]>=0)
#Step required to perform calcualtions with the array S
TempS=convert(Array{Any},zeros(K*T,1,E))
for e in 1:E
for j in 1:K*T
TempS[j,1,e]=S[j,1,e]
end
end
Cons1=convert(Array{Any},zeros(K,1,E))
for e in 1:E
for k in 1:K
Cons1[k,1,e]=sum(TempS[(k-1)*T+1:(1+(k-1))*T],dims=1)
end
end
Cons1
```

The array Cons1 is a bunch of expresions like this one:

GenericAffExpr{Float64,VariableRef}[S[1,1,1] + S[2,1,1]]

I am traying to use Cons1 in a constraint:

`@constraint(m, [i = 1:6], Cons1[i,1,1] - 1 <= 0)`

Obtaining the following error:

MethodError: promote_operation(::typeof(MutableArithmetics.sub_mul), ::Type{Array{GenericAffExpr{Float64,VariableRef},1}}, ::Type{Int64}) is ambiguous. Candidates:

promote_operation(op::Union{typeof(+), typeof(-), typeof(MutableArithmetics.add_mul), typeof(MutableArithmetics.sub_mul)}, A::Type{#s13} where #s13<:Array, α::Type{#s12} where #s12<:Number) in MutableArithmetics at C:\Users\danuk.julia\packages\MutableArithmetics\bPWR4\src\interface.jl:46

promote_operation(op::Union{typeof(MutableArithmetics.add_mul), typeof(MutableArithmetics.sub_mul)}, T::Type, args::Vararg{Type,N}) where N in MutableArithmetics at C:\Users\danuk.julia\packages\MutableArithmetics\bPWR4\src\shortcuts.jl:63

Possible fix, define

promote_operation(::Union{typeof(MutableArithmetics.add_mul), typeof(MutableArithmetics.sub_mul)}, ::Type{#s13} where #s13<:Array, ::Type{#s12} where #s12<:Number)

Thank you in advance for any help you can give me.