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qiskit.opflow.gradients.Hessian.get_hessian

Hessian.get_hessian(operator, params=None)[source]

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 (Union[Tuple[ParameterExpression, ParameterExpression], List[Tuple[ParameterExpression, ParameterExpression]], List[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.

Return type

OperatorBase

Returns

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

Raises

  • ValueError – If params contains a parameter not present in operator.

  • ValueError – 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 – If the operator does not include a StateFn given by a quantum circuit

  • TypeError – If the parameters were given in an unsupported format.

  • Exception – Unintended code is reached

  • MissingOptionalLibraryError – jax not installed