I am recently looking into automatic differentiation, as implemented by `ForwardDiff.jl`

. The manual says functions that call blas are not supported, therefore any functions containing `eig`

are not supported. I think I partly understand the reason behind this statement.

However, I noticed that `eigh`

(eigen decomposition of Hermitian matrix) is supported by `AlgoPy`

(https://github.com/b45ch1/algopy), a package providing automatic differentiation in python. This is quite unexpected since derivatives of eigenvectors are not well defined since eigenvectors can be multiplied by arbitrary number. I wonder how `AlgoPy`

supports eigen decomposition and whether itās doable in julia.