95 lines
7.6 KiB
Plaintext
95 lines
7.6 KiB
Plaintext
---
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title: DerivativeBase
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description: API reference for qiskit.opflow.gradients.DerivativeBase
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in_page_toc_min_heading_level: 1
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python_api_type: class
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python_api_name: qiskit.opflow.gradients.DerivativeBase
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---
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# DerivativeBase
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<Class id="qiskit.opflow.gradients.DerivativeBase" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.46/qiskit/opflow/gradients/derivative_base.py" signature="qiskit.opflow.gradients.DerivativeBase" modifiers="class">
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Bases: [`ConverterBase`](qiskit.opflow.converters.ConverterBase "qiskit.opflow.converters.converter_base.ConverterBase")
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Deprecated: Base class for differentiating opflow objects.
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Converter for differentiating opflow objects and handling things like properly differentiating combo\_fn’s and enforcing product rules when operator coefficients are parameterized.
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This is distinct from CircuitGradient converters which use quantum techniques such as parameter shifts and linear combination of unitaries to compute derivatives of circuits.
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CircuitGradient - uses quantum techniques to get derivatives of circuits DerivativeBase - uses classical techniques to differentiate opflow data structures
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<Admonition title="Deprecated since version 0.24.0" type="danger">
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The class `qiskit.opflow.gradients.derivative_base.DerivativeBase` is deprecated as of qiskit-terra 0.24.0. It will be removed in the Qiskit 1.0 release. For code migration guidelines, visit [https://qisk.it/opflow\_migration](https://qisk.it/opflow_migration).
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</Admonition>
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## Methods
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### convert
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<Function id="qiskit.opflow.gradients.DerivativeBase.convert" signature="convert(operator, params=None)" modifiers="abstract">
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**Parameters**
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* **operator** ([*OperatorBase*](qiskit.opflow.OperatorBase "qiskit.opflow.operator_base.OperatorBase")) – The operator we are taking the gradient, Hessian or QFI of
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* **params** ([*ParameterVector*](qiskit.circuit.ParameterVector "qiskit.circuit.parametervector.ParameterVector") *|*[*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.parameterexpression.ParameterExpression") *|*[*List*](https://docs.python.org/3/library/typing.html#typing.List "(in Python v3.12)")*\[*[*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.parameterexpression.ParameterExpression")*] | None*) – The parameters we are taking the gradient, Hessian or QFI with respect to.
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**Returns**
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An operator whose evaluation yields the gradient, Hessian or QFI.
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**Raises**
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[**ValueError**](https://docs.python.org/3/library/exceptions.html#ValueError "(in Python v3.12)") – If `params` contains a parameter not present in `operator`.
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**Return type**
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[*OperatorBase*](qiskit.opflow.OperatorBase "qiskit.opflow.operator_base.OperatorBase")
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</Function>
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### gradient\_wrapper
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<Function id="qiskit.opflow.gradients.DerivativeBase.gradient_wrapper" signature="gradient_wrapper(operator, bind_params, grad_params=None, backend=None, expectation=None)">
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Get a callable function which provides the respective gradient, Hessian or QFI for given parameter values. This callable can be used as gradient function for optimizers.
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**Parameters**
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* **operator** ([*OperatorBase*](qiskit.opflow.OperatorBase "qiskit.opflow.operator_base.OperatorBase")) – The operator for which we want to get the gradient, Hessian or QFI.
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* **bind\_params** ([*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.parameterexpression.ParameterExpression") *|*[*ParameterVector*](qiskit.circuit.ParameterVector "qiskit.circuit.parametervector.ParameterVector") *|*[*List*](https://docs.python.org/3/library/typing.html#typing.List "(in Python v3.12)")*\[*[*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.parameterexpression.ParameterExpression")*]*) – The operator parameters to which the parameter values are assigned.
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* **grad\_params** ([*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.parameterexpression.ParameterExpression") *|*[*ParameterVector*](qiskit.circuit.ParameterVector "qiskit.circuit.parametervector.ParameterVector") *|*[*List*](https://docs.python.org/3/library/typing.html#typing.List "(in Python v3.12)")*\[*[*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.parameterexpression.ParameterExpression")*] |* [*Tuple*](https://docs.python.org/3/library/typing.html#typing.Tuple "(in Python v3.12)")*\[*[*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.parameterexpression.ParameterExpression")*,* [*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.parameterexpression.ParameterExpression")*] |* [*List*](https://docs.python.org/3/library/typing.html#typing.List "(in Python v3.12)")*\[*[*Tuple*](https://docs.python.org/3/library/typing.html#typing.Tuple "(in Python v3.12)")*\[*[*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.parameterexpression.ParameterExpression")*,* [*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.parameterexpression.ParameterExpression")*]] | None*) – The parameters with respect to which we are taking the gradient, Hessian or QFI. If grad\_params = None, then grad\_params = bind\_params
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* **backend** ([*Backend*](qiskit.providers.Backend "qiskit.providers.backend.Backend") *|*[*QuantumInstance*](qiskit.utils.QuantumInstance "qiskit.utils.quantum_instance.QuantumInstance") *| None*) – The quantum backend or QuantumInstance to use to evaluate the gradient, Hessian or QFI.
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* **expectation** ([*ExpectationBase*](qiskit.opflow.expectations.ExpectationBase "qiskit.opflow.expectations.expectation_base.ExpectationBase") *| None*) – The expectation converter to be used. If none is set then PauliExpectation() is used.
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**Returns**
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Function to compute a gradient, Hessian or QFI. The function takes an iterable as argument which holds the parameter values.
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**Return type**
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[*Callable*](https://docs.python.org/3/library/typing.html#typing.Callable "(in Python v3.12)")\[\[[*Iterable*](https://docs.python.org/3/library/typing.html#typing.Iterable "(in Python v3.12)")], [*ndarray*](https://numpy.org/doc/stable/reference/generated/numpy.ndarray.html#numpy.ndarray "(in NumPy v2.0)")]
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</Function>
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### parameter\_expression\_grad
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<Function id="qiskit.opflow.gradients.DerivativeBase.parameter_expression_grad" signature="parameter_expression_grad(param_expr, param)" modifiers="static">
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Get the derivative of a parameter expression w\.r.t. the given parameter.
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<Admonition title="Deprecated since version 0.18.0" type="danger">
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The method `qiskit.opflow.gradients.derivative_base.DerivativeBase.parameter_expression_grad()` is deprecated as of qiskit-terra 0.18.0. It will be removed in the Qiskit 1.0 release. Instead, use the ParameterExpression.gradient method.
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</Admonition>
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**Parameters**
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* **param\_expr** ([*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.parameterexpression.ParameterExpression")) – The Parameter Expression for which we compute the derivative
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* **param** ([*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.parameterexpression.ParameterExpression")) – Parameter w\.r.t. which we want to take the derivative
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**Returns**
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ParameterExpression representing the gradient of param\_expr w\.r.t. param
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**Return type**
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[*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.parameterexpression.ParameterExpression") | [float](https://docs.python.org/3/library/functions.html#float "(in Python v3.12)")
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</Function>
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</Class>
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