Symbolic matrix multiplication to polynomial

General Usage
1

Can I get a polynomial out of this?

julia> @variables x[1:3] y[1:3] 
3-element Vector{Symbolics.Arr{Num}}:
 x[1:3]
 y[1:3]

julia> A = [
            1   2  14
           -5   2  -3
            8  19  -2
       ]
3×3 Matrix{Int64}:
  1   2  14
 -5   2  -3
  8  19  -2

julia> y'A*x
adjoint([1 -5 8; 2 2 19; 14 -3 -2]*y)*x

julia> collect(y'A*x)
0-dimensional Array{Num, 0}:
adjoint([1 -5 8; 2 2 19; 14 -3 -2]*y)*x
2

Collect the array variables immediately

julia> x,y = collect.((x,y))
(Num[x[1], x[2], x[3]], Num[y[1], y[2], y[3]])

julia> y'A*x
(14y[1] - 3y[2] - 2y[3])*x[3] + (8y[3] + y[1] - 5y[2])*x[1] + (2y[1] + 2y[2] + 19y[3])*x[2]
1 Like