In [1]:
include("plotregion.jl")
using Plots

plotlyjs()
ezcontour!(x, y, f) = begin
    X = repmat(x', length(y), 1)
    Y = repmat(y, 1, length(x))
    # Evaluate each f(x, y)
    Z = map((x,y) -> (f([x,y])), X, Y)
    plot!(x, y, Z, st=:contour)
end