qiskit.circuit.ParameterExpression

class ParameterExpression(symbol_map, expr)

ParameterExpression class to enable creating expressions of Parameters.

Create a new ParameterExpression.

Not intended to be called directly, but to be instantiated via operations on other Parameter or ParameterExpression objects.

Parameters

• symbol_map (Dict[Parameter, [ParameterExpression, float, or int]]) – Mapping of Parameter instances to the sympy.Symbol serving as their placeholder in expr.

• expr (sympy.Expr) – Expression of sympy.Symbol s.

__init__(symbol_map, expr)

Create a new ParameterExpression.

Not intended to be called directly, but to be instantiated via operations on other Parameter or ParameterExpression objects.

Parameters

• symbol_map (Dict[Parameter, [ParameterExpression, float, or int]]) – Mapping of Parameter instances to the sympy.Symbol serving as their placeholder in expr.

• expr (sympy.Expr) – Expression of sympy.Symbol s.

Methods

__init__(symbol_map, expr)	Create a new ParameterExpression.
arccos()	Arccos of a ParameterExpression
arcsin()	Arcsin of a ParameterExpression
arctan()	Arctan of a ParameterExpression
assign(parameter, value)	Assign one parameter to a value, which can either be numeric or another parameter expression.
bind(parameter_values)	Binds the provided set of parameters to their corresponding values.
conjugate()	Return the conjugate.
cos()	Cosine of a ParameterExpression
exp()	Exponential of a ParameterExpression
gradient(param)	Get the derivative of a parameter expression w.r.t.
is_real()	Return whether the expression is real
log()	Logarithm of a ParameterExpression
sin()	Sine of a ParameterExpression
subs(parameter_map)	Returns a new Expression with replacement Parameters.
tan()	Tangent of a ParameterExpression

Attributes

parameters

Returns a set of the unbound Parameters in the expression.

arccos()

Arccos of a ParameterExpression

arcsin()

Arcsin of a ParameterExpression

arctan()

Arctan of a ParameterExpression

assign(parameter, value)

Assign one parameter to a value, which can either be numeric or another parameter expression.

Parameters

• parameter (Parameter) – A parameter in this expression whose value will be updated.

• value (Union[ParameterExpression, float]) – The new value to bind to.

Return type

ParameterExpression

Returns

A new expression parameterized by any parameters which were not bound by assignment.

bind(parameter_values)

Binds the provided set of parameters to their corresponding values.

Parameters

parameter_values (Dict) – Mapping of Parameter instances to the numeric value to which they will be bound.

Raises

• CircuitError –

  • If parameter_values contains Parameters outside those in self. - If a non-numeric value is passed in parameter_values.

• ZeroDivisionError –

  • If binding the provided values requires division by zero.

Return type

ParameterExpression

Returns

A new expression parameterized by any parameters which were not bound by parameter_values.

conjugate()

Return the conjugate.

Return type

ParameterExpression

cos()

Cosine of a ParameterExpression

exp()

Exponential of a ParameterExpression

gradient(param)

Get the derivative of a parameter expression w.r.t. a specified parameter expression.

Parameters

param (Parameter) – Parameter w.r.t. which we want to take the derivative

Return type

Union[ParameterExpression, float]

Returns

ParameterExpression representing the gradient of param_expr w.r.t. param

is_real()

Return whether the expression is real

log()

Logarithm of a ParameterExpression

property parameters

Returns a set of the unbound Parameters in the expression.

Return type

Set

sin()

Sine of a ParameterExpression

subs(parameter_map)

Returns a new Expression with replacement Parameters.

Parameters

parameter_map (Dict) – Mapping from Parameters in self to the ParameterExpression instances with which they should be replaced.

Raises

CircuitError –

• If parameter_map contains Parameters outside those in self. - If the replacement Parameters in parameter_map would result in a name conflict in the generated expression.

Return type

ParameterExpression

Returns

A new expression with the specified parameters replaced.

tan()

Tangent of a ParameterExpression