Comment by fmap

Isn't this an old idea? E.g., here's a textbook on optimization algorithms for matrix manifolds https://press.princeton.edu/absil and here's a library that implements this in python for the Stiefel manifold that's the subject of this blog post: https://pymanopt.org/docs/stable/manifolds.html#module-pyman...

What is novel about the approach in the blog post? Serious question, I really can't tell after reading the post.