gf_cont_struct

Synopsis

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 parameterization is done via a vector datum, dataname_init and dataname_final should store two given values of this datum determining the parameterization, 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’;
  • ‘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);
  • ‘singularities’, int SING
    activates tools for detection and treatment of singular points (1 for limit points, 2 for bifurcation points and points requiring special branching techniques);
  • ‘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
    total number of the linear combinations of one couple of reference vectors when searching for new tangent predictions during location of new one-sided branches (the default value is 40);
  • ‘nb_span’, int NSPAN
    total number of the couples of the 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.).