using Zygote
using LinearAlgebra: norm

g(x::Vector{<:Real}) = 2x'x

v = [1, 3, 6]
@assert g'(v) == 4*v

function f(x)
   if x > 0
       return 30x
   else
       return 50x
   end
end

@assert f'(3) == 30
@assert f'(-1) == 50

function affine(A, b)
    return (x) -> A*x + b
end

A = [1 2; 3 4]
b = [30, 30]

h = affine(A, b)

@assert jacobian(h, [1,2]) == (A,)