serif::solver::Backtracking options.hpp double double serif::solver::Backtracking::initial_step initial_step serif::solver::Backtracking::initial_step {1.0} double double serif::solver::Backtracking::contraction contraction serif::solver::Backtracking::contraction {0.5} double double serif::solver::Backtracking::fraction_to_boundary fraction_to_boundary serif::solver::Backtracking::fraction_to_boundary {0.9} double double serif::solver::Backtracking::sufficient_decrease sufficient_decrease serif::solver::Backtracking::sufficient_decrease {1.0e-4} double double serif::solver::Backtracking::minimum_step minimum_step serif::solver::Backtracking::minimum_step {1.0e-8} int int serif::solver::Backtracking::maximum_trials maximum_trials serif::solver::Backtracking::maximum_trials {20} bool bool serif::solver::Backtracking::geometry_preflight geometry_preflight serif::solver::Backtracking::geometry_preflight {true} void void serif::solver::Backtracking::validate () const validate serif::solver::Backtracking::validate Require a decreasing, finite sequence of positive trial lengths. Shorten a Newton step until the complete residual merit decreases sufficiently. serif::solver::Backtrackingcontraction serif::solver::Backtrackingfraction_to_boundary serif::solver::Backtrackinggeometry_preflight serif::solver::Backtrackinginitial_step serif::solver::Backtrackingmaximum_trials serif::solver::Backtrackingminimum_step serif::solver::Backtrackingsufficient_decrease serif::solver::Backtrackingvalidate