function l(k,t)
    r=1
    for j=1:n
        if j!=k
            r=r*(t-x[j])/(x[k]-x[j])
        end
    end
    return r
end
x=[1,2,3,5,6,7]
y=rand(6)
function p(t)
    s=0
    for k=1:n
        s=s+y[k]*l(k,t)
    end
    return s
end
using Plots
display(scatter(x,y))
xs=[1:0.1:7;];
n=6
display(plot!(xs,p.(xs)))