qc2.algorithms.utils.helper_funcs
=================================

.. py:module:: qc2.algorithms.utils.helper_funcs

.. autoapi-nested-parse::

   Module containing general helper functions.



Functions
---------

.. autoapisummary::

   qc2.algorithms.utils.helper_funcs.vector_to_skew_symmetric
   qc2.algorithms.utils.helper_funcs.skew_symmetric_to_vector
   qc2.algorithms.utils.helper_funcs.reshape_2
   qc2.algorithms.utils.helper_funcs.get_non_redundant_indices


Module Contents
---------------

.. py:function:: vector_to_skew_symmetric(vector: Union[List[float], numpy.ndarray]) -> numpy.ndarray

   Map a vector to an anti-symmetric matrix with np.tril_indices.

   :param vector: 1d tensor
   :type vector: Union[List[float], np.ndarray]

   :returns:     A skew-symmetric matrix corresponding to the input vector.
   :rtype: np.ndarray

   **Example**

   The resulting matrix for `np.array([1,2,3,4,5,6])` is:

   .. math::
       \begin{pmatrix}
           0 & -1 & -2 & -4\\
           1 &  0 & -3 & -5\\
           2 &  3 &  0 & -6\\
           4 &  5 &  6 &  0
       \end{pmatrix}


.. py:function:: skew_symmetric_to_vector(kappa_matrix: numpy.ndarray) -> numpy.ndarray

   Converts a skew-symmetric matrix to a 1D vector.

   This function extracts the lower triangular part of a skew-symmetric
   matrix and flattens it to a 1D vector.

   :param kappa_matrix: A skew-symmetric matrix.
   :type kappa_matrix: np.ndarray

   :returns:     A 1-dimensional vector containing the elements of the lower
                 triangular part of the input matrix.
   :rtype: np.ndarray


.. py:function:: reshape_2(arr: Union[List[float], numpy.ndarray], dim: int, dim_2: Optional[int] = None) -> numpy.ndarray

   Reshapes a flattened 2D array into a 2D array with specified dimensions.

   :param arr: A flattened array or list to be
               reshaped.
   :type arr: Union[List[float], np.ndarray]
   :param dim: The first dimension of the reshaped array.
   :type dim: int
   :param dim_2: The second dimension of the reshaped array.
                 If None, it is set equal to dim.
   :type dim_2: int, optional

   :returns:     A 2-dimensional array reshaped according to the specified
                 dimensions.
   :rtype: np.ndarray


.. py:function:: get_non_redundant_indices(occ_idx: numpy.ndarray, act_idx: numpy.ndarray, virt_idx: numpy.ndarray, freeze_active: bool) -> numpy.ndarray

   Calculates the non-redundant indices for orbital parameters.

   :param occ_idx: Indices of occupied orbitals.
   :type occ_idx: np.ndarray
   :param act_idx: Indices of active orbitals.
   :type act_idx: np.ndarray
   :param virt_idx: Indices of virtual orbitals.
   :type virt_idx: np.ndarray
   :param freeze_active: If True, active orbitals are frozen.
   :type freeze_active: bool

   :returns:     Indices of non-redundant orbital rotation parameters.
   :rtype: np.ndarray