optimization_variable

Graph.optimization_variable(count, lower_bound, upper_bound, is_lower_unbounded=False, is_upper_unbounded=False, initial_values=None, *, name=None)

Create a 1D Tensor of optimization variables, which can be bounded, semi-bounded, or unbounded.

Use this function to create a sequence of variables that can be tuned by the optimizer (within specified bounds) in order to minimize the cost function.

Parameters

• count (int) – The number $N$
• lower_bound (float) – The lower bound $v_\mathrm{min}$
• upper_bound (float) – The upper bound $v_\mathrm{max}$
• is_lower_unbounded (bool , optional) – Defaults to False. Set this flag to True to define a semi-bounded variable with lower bound $-\infty$
• is_upper_unbounded (bool , optional) – Defaults to False. Set this flag to True to define a semi-bounded variable with upper bound $+\infty$
• initial_values (np.ndarray or List [ np.ndarray ] or None , optional) – Initial values for the optimization variable. You can either provide a single initial value, or a list of them. Note that all optimization variables in a graph with non-default initial values must have the same length. That is, you must set them either as a single array or a list of arrays of the same length. Defaults to None, meaning the optimizer initializes the variables with random values.
• name (str or None , optional) – The name of the node.

Returns

The sequence $\{v_n\}$ of $N$ optimization variables. If both is_lower_unbounded and is_upper_unbounded are False, these variables are bounded such that $v_\mathrm{min}\leq v_n\leq v_\mathrm{max}$. If one of the flags is True (for example is_lower_unbounded=True), these variables are semi-bounded (for example $-\infty \leq v_n \leq v_\mathrm{max}$). If both of them are True, then these variables are unbounded and satisfy that $-\infty \leq v_n \leq +\infty$

Return type

Tensor

SEE ALSO

Graph.anchored_difference_bounded_variables : Create anchored optimization variables with a difference bound.

Graph.complex_optimizable_pwc_signal : Create a complex optimizable Pwc signal.

Graph.optimizable_scalar : Create an optimization scalar.

Graph.real_optimizable_pwc_signal : Create a real optimizable Pwc signal.

boulderopal.run_optimization : Function to find the minimum of a generic function.

Examples

Perform a simple optimization task.

>>> variables = graph.optimization_variable(
...     2, lower_bound=0, upper_bound=1, name="variables"
... )
>>> x = variables[0]
>>> y = variables[1]
>>> cost = (x - 0.1) ** 2 + graph.sin(y) ** 2
>>> cost.name = "cost"
>>> result = bo.run_optimization(
...     graph=graph, cost_node_name="cost", output_node_names="variables"
... )
>>> result["cost"]
0.0
>>> result["output"]["variables"]["value"]
array([0.1, 0.])

See examples about optimal control of quantum systems in the How to optimize controls in arbitrary quantum systems using graphs user guide.