def _shrink_towards_best(objective_function,<EOL>simplex,<EOL>best_index,<EOL>shrinkage,<EOL>batch_evaluate_objective):
<EOL>best_vertex = simplex[best_index]<EOL>shrunk_simplex = best_vertex + shrinkage * (simplex - best_vertex)<EOL>objective_at_shrunk_simplex, evals = _evaluate_objective_multiple(<EOL>objective_function,<EOL>shrunk_simplex,<EOL>batch_evaluate_objective)<EOL>return (False,<EOL>shrunk_simplex,<EOL>objective_at_shrunk_simplex,<EOL>evals)<EOL>
Shrinks the simplex around the best vertex.