Thanks! So replacing Fx:: Array{Float64} with Fx:: Circulant{Float64}? When I am defining structs it is a good idea to be as specific as possible regarding the type then, instead of using Array I should use Matrix, or Vector depending on the situation? I have wrapped the nested for loop in its own function too, this speeds the calculation up to about 60 seconds.
I wanted to do it this way more for my own satisfaction, I like to try understanding a concept by coding it myself first. I shall look into DSP, I imagine it is a lot fast than my code…