function norms(v)

    s1 = 0.0
    s2 = 0.0
    sinf = 0.0
    # here one can define a variable n = length(v) and then do loop in the typical way for i in 1:n, but julia also offers eachindex(v) which immediately finds the correct index for its input v.
    for i in eachindex(v)
        s1 = s1 + abs(v[i])
        s2 = s2 + v[i]^2
        abs_v = abs(v)
        if sinf < abs_v
            sinf = abs_v
        end
    end
    return s1,s2,sinf
end