1Blurb:: 2Step length-based stopping criteria for derivative-free optimizers 3 4Description:: 5The \c variable_tolerance keyword defines the minimum step length allowed 6by the optimizer and is used to determine convergence. It is 7applicable to \c asynch_pattern_search, \c coliny_cobyla, \c 8coliny_pattern_search, \c coliny_solis_wets, and \c 9mesh_adaptive_search. 10 11<b> Default Behavior </b> 12 13The default value varies according to method as follows: 14 15\li \c asynch_pattern_search: 1.0e-2 16\li \c coliny_cobyla: 1.0e-4 17\li \c coliny_pattern_search: 1.0e-5 18\li \c coliny_solis_wets: 1.0e-6 19\li \c mesh_adaptive_search: 1.0e-6 20 21<b> Usage Tips </b> 22 23It is recommended that \c variable_tolerance be set to a value for which 24changes of that scale in parameter values cause negligible changes in 25the objective function. 26 27Topics:: 28 29Examples:: 30 31Three example method input blocks appear below. 32 33For \c asynch_pattern_search: 34\verbatim 35method 36 asynch_pattern_search 37 contraction_factor = 0.25 38 variable_tolerance = 1.e-4 39 solution_target = 1.e-6 40 max_function_evaluations 500 41 constraint_tolerance 1.e-6 42\endverbatim 43 44For \c coliny_pattern_search: 45\verbatim 46method 47 coliny_pattern_search 48 initial_delta = .2 49 variable_tolerance = 1.e-4 50 max_iterations 100 51 solution_accuracy = 1.e-6 52 seed = 1234 53 max_function_evaluations = 1000 54\endverbatim 55 56For \c mesh_adaptive_search 57\verbatim 58method 59 mesh_adaptive_search 60 variable_tolerance = 0.01 61 seed = 1234 62\endverbatim 63 64Theory:: 65Faq:: 66See_Also:: 67