--- title: POWELL (v0.46) description: API reference for qiskit.algorithms.optimizers.POWELL in qiskit v0.46 source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/qiskit/0.46/qiskit.algorithms.optimizers.POWELL --- # POWELL *class* `qiskit.algorithms.optimizers.POWELL(maxiter=None, maxfev=1000, disp=False, xtol=0.0001, tol=None, options=None, **kwargs)` [GitHub](https://github.com/qiskit/qiskit/tree/stable/0.46/qiskit/algorithms/optimizers/powell.py) Bases: [`SciPyOptimizer`](/docs/api/qiskit/0.46/qiskit.algorithms.optimizers.SciPyOptimizer "qiskit.algorithms.optimizers.scipy_optimizer.SciPyOptimizer") Powell optimizer. The Powell algorithm performs unconstrained optimization; it ignores bounds or constraints. Powell is a *conjugate direction method*: it performs sequential one-dimensional minimization along each directional vector, which is updated at each iteration of the main minimization loop. The function being minimized need not be differentiable, and no derivatives are taken. Uses scipy.optimize.minimize Powell. For further detail, please refer to See [https://docs.scipy.org/doc/scipy/reference/generated/scipy.optimize.minimize.html](https://docs.scipy.org/doc/scipy/reference/generated/scipy.optimize.minimize.html) **Parameters** - **maxiter** ([*int*](https://docs.python.org/3/library/functions.html#int) *| None*) – Maximum allowed number of iterations. If both maxiter and maxfev are set, minimization will stop at the first reached. - **maxfev** ([*int*](https://docs.python.org/3/library/functions.html#int)) – Maximum allowed number of function evaluations. If both maxiter and maxfev are set, minimization will stop at the first reached. - **disp** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) – Set to True to print convergence messages. - **xtol** ([*float*](https://docs.python.org/3/library/functions.html#float)) – Relative error in solution xopt acceptable for convergence. - **tol** ([*float*](https://docs.python.org/3/library/functions.html#float) *| None*) – Tolerance for termination. - **options** ([*dict*](https://docs.python.org/3/library/stdtypes.html#dict) *| None*) – A dictionary of solver options. - **kwargs** – additional kwargs for scipy.optimize.minimize. ## Attributes ### bounds\_support\_level Returns bounds support level ### gradient\_support\_level Returns gradient support level ### initial\_point\_support\_level Returns initial point support level ### is\_bounds\_ignored Returns is bounds ignored ### is\_bounds\_required Returns is bounds required ### is\_bounds\_supported Returns is bounds supported ### is\_gradient\_ignored Returns is gradient ignored ### is\_gradient\_required Returns is gradient required ### is\_gradient\_supported Returns is gradient supported ### is\_initial\_point\_ignored Returns is initial point ignored ### is\_initial\_point\_required Returns is initial point required ### is\_initial\_point\_supported Returns is initial point supported ### setting Return setting ### settings ## Methods ### get\_support\_level `get_support_level()` Return support level dictionary ### gradient\_num\_diff *static* `gradient_num_diff(x_center, f, epsilon, max_evals_grouped=None)` We compute the gradient with the numeric differentiation in the parallel way, around the point x\_center. **Parameters** - **x\_center** (*ndarray*) – point around which we compute the gradient - **f** (*func*) – the function of which the gradient is to be computed. - **epsilon** ([*float*](https://docs.python.org/3/library/functions.html#float)) – the epsilon used in the numeric differentiation. - **max\_evals\_grouped** ([*int*](https://docs.python.org/3/library/functions.html#int)) – max evals grouped, defaults to 1 (i.e. no batching). **Returns** the gradient computed **Return type** grad ### minimize `minimize(fun, x0, jac=None, bounds=None)` Minimize the scalar function. **Parameters** - **fun** (*Callable\[\[POINT],* [*float*](https://docs.python.org/3/library/functions.html#float)*]*) – The scalar function to minimize. - **x0** (*POINT*) – The initial point for the minimization. - **jac** (*Callable\[\[POINT], POINT] | None*) – The gradient of the scalar function `fun`. - **bounds** ([*list*](https://docs.python.org/3/library/stdtypes.html#list)*\[*[*tuple*](https://docs.python.org/3/library/stdtypes.html#tuple)*\[*[*float*](https://docs.python.org/3/library/functions.html#float)*,* [*float*](https://docs.python.org/3/library/functions.html#float)*]] | None*) – Bounds for the variables of `fun`. This argument might be ignored if the optimizer does not support bounds. **Returns** The result of the optimization, containing e.g. the result as attribute `x`. **Return type** [OptimizerResult](/docs/api/qiskit/0.46/qiskit.algorithms.optimizers.OptimizerResult "qiskit.algorithms.optimizers.OptimizerResult") ### print\_options `print_options()` Print algorithm-specific options. ### set\_max\_evals\_grouped `set_max_evals_grouped(limit)` Set max evals grouped ### set\_options `set_options(**kwargs)` Sets or updates values in the options dictionary. The options dictionary may be used internally by a given optimizer to pass additional optional values for the underlying optimizer/optimization function used. The options dictionary may be initially populated with a set of key/values when the given optimizer is constructed. **Parameters** **kwargs** ([*dict*](https://docs.python.org/3/library/stdtypes.html#dict)) – options, given as name=value. ### wrap\_function *static* `wrap_function(function, args)` Wrap the function to implicitly inject the args at the call of the function. **Parameters** - **function** (*func*) – the target function - **args** ([*tuple*](https://docs.python.org/3/library/stdtypes.html#tuple)) – the args to be injected **Returns** wrapper **Return type** function\_wrapper