1 core.parameters.Parameter

core.parameters.Parameter(name, value=0.0)

An updatable constant for optimization problems.

Unlike Constant, a Parameter’s value can be changed between solves without rebuilding the problem structure. This enables fast re-solves when only numerical values change (not problem structure).

Parameters participate in expression building just like variables, but their values are fixed during each solve. Changing a parameter value and re-solving uses cached problem structure.

1.1 Parameters

Name	Type	Description	Default
name	str	Unique identifier for this parameter.	required
value	float | int | ArrayLike	Initial value (scalar or array).	0.0

1.2 Example

from optyx import Variable, Parameter, Problem

x = Variable(“x”, lb=0) price = Parameter(“price”, value=100)

prob = Problem().maximize(price * x - x**2).subject_to(x <= 10)

2 Initial solve

sol1 = prob.solve()

3 Price changes - fast re-solve

price.set(120) sol2 = prob.solve() # Uses cached structure

3.1 Attributes

Name	Description
value	Get the current parameter value.

3.2 Methods

Name	Description
evaluate	Evaluate the parameter (returns current value).
get_variables	Return all variables this expression depends on.
set	Update the parameter value.

3.2.1 evaluate

core.parameters.Parameter.evaluate(values)

Evaluate the parameter (returns current value).

Parameters evaluate to their stored value, not from the values dict. This allows parameters to be updated independently of solve calls.

3.2.1.1 Parameters

Name	Type	Description	Default
values	Mapping[str, ArrayLike | float]	Variable values (not used for parameters).	required

3.2.1.2 Returns

Name	Type	Description
	NDArray[np.floating] | float	The current parameter value.

3.2.2 get_variables

core.parameters.Parameter.get_variables()

Return all variables this expression depends on.

Parameters are not variables - they return an empty set.

3.2.3 set

core.parameters.Parameter.set(value)

Update the parameter value.

This can be called between solves to change the parameter value without rebuilding the problem structure.

3.2.3.1 Parameters

Name	Type	Description	Default
value	float | int | ArrayLike	New value (scalar or array, must match original shape).	required

3.2.3.2 Raises

Name	Type	Description
	ValueError	If array shape doesn’t match original.

3.2.3.3 Example

price = Parameter(“price”, value=100) price.set(120) # Update for next solve price.value 120.0