Hessian

qiskit.opflow.gradients.Hessian(hess_method='param_shift', **kwargs)

Bases: HessianBase

Deprecated: Compute the Hessian of an expected value.

Deprecated since version 0.24.0

The class qiskit.opflow.gradients.hessian.Hessian is deprecated as of qiskit-terra 0.24.0. It will be removed no earlier than 3 months after the release date. For code migration guidelines, visit https://qisk.it/opflow_migration (opens in a new tab).

Attributes

hess_method

Returns CircuitGradient.

Returns

CircuitGradient.

Methods

convert

convert(operator, params=None)

Parameters

operator (OperatorBase) – The operator for which we compute the Hessian
params (Tuple (opens in a new tab)[ParameterExpression, ParameterExpression] | List (opens in a new tab)[Tuple (opens in a new tab)[ParameterExpression, ParameterExpression]] | List (opens in a new tab)[ParameterExpression] | ParameterVector | None) – The parameters we are computing the Hessian with respect to Either give directly the tuples/list of tuples for which the second order derivative is to be computed or give a list of parameters to build the full Hessian for those parameters. If not explicitly passed, the full Hessian is constructed. The parameters are then inferred from the operator and sorted by name.

Returns

An operator whose evaluation yields the Hessian

Return type

OperatorBase

get_hessian

get_hessian(operator, params=None)

Get the Hessian for the given operator w.r.t. the given parameters

Parameters

operator (OperatorBase) – Operator w.r.t. which we take the Hessian.
params (Tuple (opens in a new tab)[ParameterExpression, ParameterExpression] | List (opens in a new tab)[Tuple (opens in a new tab)[ParameterExpression, ParameterExpression]] | List (opens in a new tab)[ParameterExpression] | ParameterVector | None) – Parameters w.r.t. which we compute the Hessian. If not explicitly passed, the full Hessian is constructed. The parameters are then inferred from the operator and sorted by name.

Returns

Operator which represents the gradient w.r.t. the given params.

Raises

ValueError (opens in a new tab) – If params contains a parameter not present in operator.
ValueError (opens in a new tab) – If operator is not parameterized.
OpflowError – If the coefficient of the operator could not be reduced to 1.
OpflowError – If the differentiation of a combo_fn requires JAX but the package is not installed.
TypeError (opens in a new tab) – If the operator does not include a StateFn given by a quantum circuit
TypeError (opens in a new tab) – If the parameters were given in an unsupported format.
Exception (opens in a new tab) – Unintended code is reached
MissingOptionalLibraryError – jax not installed

Return type

OperatorBase

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