File adi.hpp: Add real-valued diffusion ADI variants, variable coefficients, and boundary-condition parameterization.
File cholesky.hpp: Add LAPACK dpotrf/dpotrs backend dispatch and batched/block variants.
File diffusion.hpp: Add structured SPD operators for periodic diffusion, 3D grids, and matrix-free stencil application.
File expv.hpp: Add adaptive step subdivision and an a posteriori error estimate for large \(|t|\|A\|\).
File gmres.hpp: Add left/right preconditioned GMRES and flexible GMRES variants.
File implicit.hpp: Add Crank-Nicolson, BDF2, and IMEX step drivers with explicit mass matrix/operator hooks.
File lanczos.hpp: Add thick-restart Lanczos and selective reorthogonalization controls.
File markov.cpp: Add concrete sequential density-of-states and histogram reweighting routines once the stochastic API moves beyond template sweep kernels.
File markov.cpp: Add OpenMP implementations for non-template stochastic routines that need backend dispatch, such as density-of-states or windowed estimators.
File minres.hpp: Replace the projection-based implementation with the standard short-recurrence MINRES iteration.
File ode.hpp: Add event detection, dense output, BDF methods, Rosenbrock/W-methods, and implicit Runge-Kutta schemes for stiff ODE systems.
File pde.hpp: Add boundary-condition objects, Helmholtz operators, variable- coefficient elliptic operators, and structured 1D/2D/3D operator builders.
File poisson.hpp: Add Neumann/periodic Poisson variants, 3D tensor-product solves, and Helmholtz shifted Poisson solves.
File preconditioner.hpp: Add SSOR, incomplete Cholesky, ILU(0), and block-Jacobi preconditioners for sparse systems.
File properties.hpp: Add optional sampled diagnostics for matrix-free symmetry and positive-definiteness checks.
File sparse.hpp: Add transpose, symmetry diagnostics, and efficient diagonal extraction utilities for sparse solvers and preconditioners.
File stencil.hpp: Add boundary-condition-aware stencil operators and compact higher- order derivative operators for gradient, divergence, curl, and Laplacian.