gistfile1.txt

using StaticArrays
using NLSolvers
using LinearAlgebra
function himmelblau(∇²f, ∇f, x)
    if !(∇²f == nothing)
        ∇²f11 = 12.0 * x[1]^2 + 4.0 * x[2] - 42.0
        ∇²f12 = 4.0 * x[1] + 4.0 * x[2]
        ∇²f21 = 4.0 * x[1] + 4.0 * x[2]
        ∇²f22 = 12.0 * x[2]^2 + 4.0 * x[1] - 26.0
        ∇²f = @SMatrix([∇²f11 ∇²f12; ∇²f21 ∇²f22])
    end

    if !(∇f == nothing)
        ∇f1 = 4.0 * x[1]^3 + 4.0 * x[1] * x[2] -
            44.0 * x[1] + 2.0 * x[1] + 2.0 * x[2]^2 - 14.0
        ∇f2 = 2.0 * x[1]^2 + 2.0 * x[2] - 22.0 +
            4.0 * x[1] * x[2] + 4.0 * x[2]^3 - 28.0 * x[2]
        ∇f = @SVector([∇f1, ∇f2])
    end

    fx = (x[1]^2 + x[2] - 11)^2 + (x[1] + x[2]^2 - 7)^2
    
    if ∇f == nothing && ∇²f == nothing
        return fx
    elseif ∇²f == nothing
        return fx, ∇f
    else
        return fx, ∇f, ∇²f
    end
end
function himmelblau(∇f, x)
    if !(∇f == nothing)
        ∇f1 = 4.0 * x[1]^3 + 4.0 * x[1] * x[2] -
            44.0 * x[1] + 2.0 * x[1] + 2.0 * x[2]^2 - 14.0
        ∇f2 = 2.0 * x[1]^2 + 2.0 * x[2] - 22.0 +
            4.0 * x[1] * x[2] + 4.0 * x[2]^3 - 28.0 * x[2]
        ∇f = @SVector([∇f1, ∇f2])
    end

    fx = (x[1]^2 + x[2] - 11)^2 + (x[1] + x[2]^2 - 7)^2
    
    if ∇f == nothing
        return fx
    else
        return fx, ∇f
    end
end

res = minimize(himmelblau, @SVector([2.0,2.0]), Newton(Direct()))
@test norm(res[3], Inf) < 1e-8