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 <literal>dataname_parameter</literal> should parametrise the model given by <literal>md</literal>. If the parametrisation is done via a vector datum, <literal>dataname_init</literal> and <literal>dataname_final</literal> should store two given values of this datum determining the parametrisation, and <literal>dataname_current</literal> serves for actual values of this datum. <literal>sc_fac</literal> 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.).