Simply define x = zeros(N+1) and similarly for y and z and obtain a Vector{Float64} instead of a Matrix{Float64}:
julia> x = zeros(N+1,1); typeof(x)
Array{Float64,2} # a matrix
julia> x = zeros(N+1); typeof(x)
Array{Float64,1} # a vector
Simply define x = zeros(N+1) and similarly for y and z and obtain a Vector{Float64} instead of a Matrix{Float64}:
julia> x = zeros(N+1,1); typeof(x)
Array{Float64,2} # a matrix
julia> x = zeros(N+1); typeof(x)
Array{Float64,1} # a vector