axiter : int, optional The maximum number of generations over which the entire population is evolved. The maximum number of function evaluations (with no polishing) is: ``(maxiter + 1) * popsize * (N - N_equal)`` popsize : int, optional A multiplier for setting the total population size. The population has ``popsize * (N - N_equal)`` individuals. This keyword is overridden if an initial population is supplied via the `init` keyword. When using ``init='sobol'`` the population size is calculated as the next power of 2 after ``popsize * (N - N_equal)``. tol : float, optional Relative tolerance for convergence, the solving stops when ``np.std(population_energies) <= atol + tol * np.abs(np.mean(population_energies))``, where and `atol` and `tol` are the absolute and relative tolerance respectively. mutation : float or tuple(float, float), optional The mutation constant. In the literature this is also known as differential weight, being denoted by F. If specified as a float it should be in the range [0, 2]. If specified as a tuple ``(min, max)`` dithering is employed. Dithering randomly changes the mutation constant on a generation by generation basis. The mutation constant for that generation is taken from U[min, max). Dithering can help speed convergence significantly. Increasing the mutation constant increases the search radius, but will slow down convergence. recombination : float, optional The recombination constant, should be in the range [0, 1]. In the literature this is also known as the crossover probability, being denoted by CR. Increasing this value allows a larger number of mutants to progress into the next generation, but at the risk of population stability. rng : {None, int, `numpy.random.Generator`}, optional ..versionchanged:: 1.15.0 As part of the `SPEC-007 `_ transition from use of `numpy.random.RandomState` to `numpy.random.Generator` this keyword was changed from `seed` to `rng`. For an interim period both keywords will continue to work (only specify one of them). After the interim period using the `seed` keyword will emit warnings. The behavior of the `seed` and `rng` keywords is outlined below. If `rng` is passed by keyword, types other than `numpy.random.Generator` are passed to `numpy.random.default_rng` to instantiate a `Generator`. If `rng` is already a `Generator` instance, then the provided instance is used. If this argument is passed by position or `seed` is passed by keyword, the behavior is: - If `seed` is None (or `np.random`), the `numpy.random.RandomState` singleton is used. - If `seed` is an int, a new `RandomState` instance is used, seeded with `seed`. - If `seed` is already a `Generator` or `RandomState` instance then that instance is used. Specify `seed`/`rng` for repeatable minimizations. disp : bool, optional Prints the evaluated `func` at every iteration. callback : callable, optional A callable called after each iteration. Has the signature: ``callback(intermediate_result: OptimizeResult)`` where ``intermediate_result`` is a keyword parameter containing an `OptimizeResult` with attributes ``x`` and ``fun``, the best solution found so far and the objective function. Note that the name of the parameter must be ``intermediate_result`` for the callback to be passed an `OptimizeResult`. The callback also supports a signature like: ``callback(x, convergence: float=val)`` ``val`` represents the fractional value of the population convergence. When ``val`` is greater than ``1.0``, the function halts. Introspection is used to determine which of the signatures is invoked. Global minimization will halt if the callback raises ``StopIteration`` or returns ``True``; any polishing is still carried out. .. versionchanged:: 1.12.0 callback accepts the ``intermediate_result`` keyword. polish : bool, optional If True (default), then `scipy.optimize.minimize` with the `L-BFGS-B` method is used to polish the best population member at the end, which can improve the minimization slightly. If a constrained problem is being studied then the `trust-constr` method is used instead. For large problems with many constraints, polishing can take a long time due to the Jacobian computations. maxfun : int, optional Set the maximum number of function evaluations. However, it probably makes more sense to set `maxiter` instead. init : str or array-like, optional Specify which type of population initialization is performed. Should be one of: - 'latinhypercube' - 'sobol' - 'halton' - 'random' - array specifying the initial population. The array should have shape ``(S, N)``, where S is the total population size and N is the number of parameters. `init` is clipped to `bounds` before use. The default is 'latinhypercube'. Latin Hypercube sampling tries to maximize coverage of the available parameter space. 'sobol' and 'halton' are superior alternatives and maximize even more the parameter space. 'sobol' will enforce an initial population size which is calculated as the next power of 2 after ``popsize * (N - N_equal)``. 'halton' has no requirements but is a bit less efficient. See `scipy.stats.qmc` for more details. 'random' initializes the population randomly - this has the drawback that clustering can occur, preventing the whole of parameter space being covered. Use of an array to specify a population could be used, for example, to create a tight bunch of initial guesses in an location where the solution is known to exist, thereby reducing time for convergence. atol : float, optional Absolute tolerance for convergence, the solving stops when ``np.std(pop) <= atol + tol * np.abs(np.mean(population_energies))``, where and `atol` and `tol` are the absolute and relative tolerance respectively. updating : {'immediate', 'deferred'}, optional If ``'immediate'``, the best solution vector is continuously updated within a single generation [4]_. This can lead to faster convergence as trial vectors can take advantage of continuous improvements in the best solution. With ``'deferred'``, the best solution vector is updated once per generation. Only ``'deferred'`` is compatible with parallelization or vectorization, and the `workers` and `vectorized` keywords can over-ride this option. workers : int or map-like callable, optional If `workers` is an int the population is subdivided into `workers` sections and evaluated in parallel (uses `multiprocessing.Pool `). Supply `-1` to use all cores available to the Process. Alternatively supply a map-like callable, such as `multiprocessing.Pool.map` for evaluating the population in parallel. This evaluation is carried out as ``workers(func, iterable)``. This option will override the `updating` keyword to `updating='deferred'` if `workers != 1`. Requires that `func` be pickleable. constraints : {NonLinearConstraint, LinearConstraint, Bounds} Constraints on the solver, over and above those applied by the `bounds` kwd. Uses the approach by Lampinen. x0 : None or array-like, optional Provides an initial guess to the minimization. Once the population has been initialized this vector replaces the first (best) member. This replacement is done even if `init` is given an initial population. ``x0.shape == (N,)``. integrality : 1-D array, optional For each decision variable, a boolean value indicating whether the decision variable is constrained to integer values. The array is broadcast to ``(N,)``. If any decision variables are constrained to be integral, they will not be changed during polishing. Only integer values lying between the lower and upper bounds are used. If there are no integer values lying between the bounds then a `ValueError` is raised. vectorized : bool, optional If ``vectorized is True``, `func` is sent an `x` array with ``x.shape == (N, S)``, and is expected to return an array of shape ``(S,)``, where `S` is the number of solution vectors to be calculated. If constraints are applied, each of the functions used to construct a `Constraint` object should accept an `x` array with ``x.shape == (N, S)``, and return an array of shape ``(M, S)``, where `M` is the number of constraint components. This option is an alternative to the parallelization offered by `workers`, and may help in optimization speed. This keyword is ignored if ``workers != 1``. This option will override the `updating` keyword to ``updating='deferred'``. Ú