Any example of explicit differentiation?

[ZedongPeng]

According to the documentation,

All solvers in JAXopt support implicit differentiation out-of-the-box. Most solvers have an implicit_diff=True|False option. When set to False, autodiff of unrolled iterates is used instead of implicit differentiation.

Is there any example of explicit differentiation by setting implicit_diff=False and unroll=True?
If I use explicit differentiation and calculate jvp, does this mean that I need to call the solver twice?

1. First, solve the problem to get the optimal solution.
2. Second, use jax.jvp and the optimal solution to calculate the jacobian and vector product.

Thanks in advance.