We know that the notation [1, 2, 3] is used to create an array. In fact, this notation denotes a special type of array, called a (column) vector in Julia, as shown in the following screenshot:
To create this as a row vector (1 2 3), use the notation [1 2 3] with spaces instead of commas. This array is of type 1 x 3 Array{Int64,2}, so it has two dimensions. (The spaces used in [1, 2, 3] are for readability only, we could have written this as [1,2,3]).
A matrix is a two- or multidimensional array (in fact, a matrix is an alias for the two-dimensional case). We can write this as follows:
Array{Int64, 1} == Vector{Int64} #> true Array{Int64, ...
