calc_area_ngon.jl

function calc_area_ngon(a,b)
if length(a) == length(b) && length(a) >= 2
    A = 0;
    for i = 1:length(a)-1
        A = A + (a[i]*b[i+1]-b[i]*a[i+1])/2;
    end
    return A
end
end