Concatenation and reshape of Array variables

[raphaelchinchilla]

I was playing around with concatenation and reshape of Array variables, and I found behaviors that seem to me to be either a bug that should be corrected or a feature design that should be changed. Consider the following code snippet:

@variables x[1:4]

var1=[x;x]

var2=reshape(x,2,2)

if we look at the resulting variables, we get:

var1
8-element Vector{Num}:
 x[1]
 x[2]
 x[3]
 x[4]
 x[1]
 x[2]
 x[3]
 x[4]

and

var2
2×2 reshape(::Symbolics.Arr{Num, 1}, 2, 2) with eltype Num:
 x[1]  x[3]
 x[2]  x[4]

I would have expected var2 to have a similar effect to doing @variables var2[1:2,1:3] and var1 to create a new vector array that references the original variable x.

What is not clear to me is whether these are design choices or a bug. I say a bug because it often happens that one needs the reshape the variable or concatenate them.

If it is a bug, could you let me know? I will try to look into fixing it. These issues seem to be somehow similar to #850 and #855 .

[shashi]

We don't have reshape implemented.

Concatenation is possible with #548 (should probably not call it stencils)