user-provided preconditioner

  • ex6.c u`` + u^{2} = f. Different matrices for the Jacobian and the preconditioner.
    Demonstrates the use of matrix-free Newton-Krylov methods in conjunction
    with a user-provided preconditioner. Input arguments are:
    -snes_mf : Use matrix-free Newton methods
    -user_precond : Employ a user-defined preconditioner. Used only with
    matrix-free methods in this example.