gf_cont_struct

This object serves for storing parameters and data used in numerical continuation of solution branches of models (for more details about continuation see the Getfem++ user documentation).

# Calling Sequence

    S = gf_cont_struct(model md, string dataname_parameter[,string dataname_init, string dataname_final, string dataname_current], scalar sc_fac[, ...])

## Description

General constructor for cont_struct objects.

This object serves for storing parameters and data used in numerical continuation of solution branches of models (for more details about continuation see the Getfem++ user documentation).

## Command list

- `S = gf_cont_struct(model md, string dataname_parameter[,string dataname_init, string dataname_final, string dataname_current], scalar sc_fac[, ...])`

  The variable `dataname_parameter` should parametrise the model given by `md`. If the parametrisation is done via a vector datum, `dataname_init` and `dataname_final` should store two given values of this datum determining the parametrisation, and `dataname_current` serves for actual values of this datum. `sc_fac` is a scale factor involved in the weighted norm used in the continuation. Additional options: - 'lsolver', string SOLVER_NAME name of the solver to be used for the incorporated linear systems (the default value is 'auto', which lets getfem choose itself); possible values are 'superlu', 'mumps' (if supported), 'cg/ildlt', 'gmres/ilu' and 'gmres/ilut'; - 'bifurcations' activates tools for detection and treatment of bifurcation points; - 'h_init', scalar HIN initial step size (the default value is 1e-2); - 'h_max', scalar HMAX maximum step size (the default value is 1e-1); - 'h_min', scalar HMIN minimum step size (the default value is 1e-5); - 'h_inc', scalar HINC factor for enlarging the step size (the default value is 1.3); - 'h_dec', scalar HDEC factor for diminishing the step size (the default value is 0.5); - 'max_iter', int MIT maximum number of iterations allowed in the correction (the default value is 10); - 'thr_iter', int TIT threshold number of iterations of the correction for enlarging the step size (the default value is 4); - 'max_res', scalar RES target residual value of a new point on the solution curve (the default value is 1e-6); - 'max_diff', scalar DIFF determines a convergence criterion for two consecutive points (the default value is 1e-6); - 'min_cos', scalar MCOS minimal value of the cosine of the angle between tangents to the solution curve at an old point and a new one (the default value is 0.9); - 'max_res_solve', scalar RES_SOLVE target residual value for the linear systems to be solved (the default value is 1e-8); - 'non-smooth' determines that some special methods for non-smooth problems can be used; - 'delta_max', scalar DMAX maximum size of division for evaluating the test function on the convex combination of two augmented Jacobians that belong to different smooth pieces (the default value is 0.005); - 'delta_min', scalar DMIN minimum size of division for evaluating the test function on the convex combination (the default value is 0.00012); - 'thr_var', scalar TVAR threshold variation for refining the division (the default value is 0.02); - 'nb_dir', int NDIR number of linear combinations of vectors in one subspace when searching for new tangent predictions during location of new one-sided branches (the default value is 40); - 'nb_comb', int NCOMB maximum number of couples of reference vectors forming the linear combinations (the default value is 1); - 'noisy' or 'very_noisy' determines how detailed information has to be displayed during the continuation process (residual values etc.).

## See Also

- getfem types

## Authors

Y. Collette