Function hvp_revrev

intermediate_source/jacobians_hessians.py:344–346

(f, primals, tangents)

# instead compose reverse-mode AD with reverse-mode AD:

def hvp_revrev(f, primals, tangents):
  _, vjp_fn = vjp(grad(f), *primals)
  return vjp_fn(*tangents)

result_hvp_revrev = hvp_revrev(f, (x,), (tangent,))
assert torch.allclose(result, result_hvp_revrev[0])