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ParameterExpression

ParameterExpression(symbol_map, expr)GitHub(opens in a new tab)

Bases: object

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.

Methods

arccos

ParameterExpression.arccos()GitHub(opens in a new tab)

Arccos of a ParameterExpression

arcsin

ParameterExpression.arcsin()GitHub(opens in a new tab)

Arcsin of a ParameterExpression

arctan

ParameterExpression.arctan()GitHub(opens in a new tab)

Arctan of a ParameterExpression

assign

ParameterExpression.assign(parameter, value)GitHub(opens in a new tab)

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

ParameterExpression.bind(parameter_values, allow_unknown_parameters=False)GitHub(opens in a new tab)

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.
  • allow_unknown_parameters (bool) – If False, raises an error if parameter_values contains Parameters in the keys outside those present in the expression. If True, any such parameters are simply ignored.

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

ParameterExpression.conjugate()GitHub(opens in a new tab)

Return the conjugate.

Return type

ParameterExpression

cos

ParameterExpression.cos()GitHub(opens in a new tab)

Cosine of a ParameterExpression

exp

ParameterExpression.exp()GitHub(opens in a new tab)

Exponential of a ParameterExpression

gradient

ParameterExpression.gradient(param)GitHub(opens in a new tab)

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, complex]

Returns

ParameterExpression representing the gradient of param_expr w.r.t. param or complex or float number

is_real

ParameterExpression.is_real()GitHub(opens in a new tab)

Return whether the expression is real

log

ParameterExpression.log()GitHub(opens in a new tab)

Logarithm of a ParameterExpression

sin

ParameterExpression.sin()GitHub(opens in a new tab)

Sine of a ParameterExpression

subs

ParameterExpression.subs(parameter_map, allow_unknown_parameters=False)GitHub(opens in a new tab)

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.
  • allow_unknown_parameters (bool) – If False, raises an error if parameter_map contains Parameters in the keys outside those present in the expression. If True, any such parameters are simply ignored.

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.

sympify

ParameterExpression.sympify()GitHub(opens in a new tab)

Return symbolic expression as a raw Sympy or Symengine object.

Symengine is used preferentially; if both are available, the result will always be a symengine object. Symengine is a separate library but has integration with Sympy.

Note

This is for interoperability only. Qiskit will not accept or work with raw Sympy or Symegine expressions in its parameters, because they do not contain the tracking information used in circuit-parameter binding and assignment.

tan

ParameterExpression.tan()GitHub(opens in a new tab)

Tangent of a ParameterExpression


Attributes

parameters

Returns a set of the unbound Parameters in the expression.

Return type

Set

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