39. Preconditioning# There are several NGSolve-tutorial dealing with using and building preconditioners 39.1. i-tutorials: You know the theory, want to know how to implement# Schwarz methods Element-wise BDDC Auxiliary Space Preconditioning 39.2. i-FEM: teaching material# Commuting AMG 39.3. Parallel Solvers# Distributed computing with NGSolve PETSc Interface 39.4. Treasure trove:# Matrix-free high order