//! Advanced PDE solvers (specialized)
//!
//! This module extends the base PDE infrastructure with:
//!
//! - **Multigrid** ([`multigrid`]): geometric multigrid (V/W/F cycles) for
//! elliptic problems on structured grids.
//! - **Spectral Element 1D** ([`spectral_element`]): high-order GLL-based
//! spectral element discretization for 1D BVPs.
//! - **Operator Splitting** ([`splitting`]): Lie-Trotter, Strang, Yoshida, and
//! adaptive Strang splitting for `du/dt = A(u) + B(u)` systems.
// Re-exports for convenience
pub use ;
pub use ;
pub use ;