code: def _ldl_get_d_and_l(ldu, pivs, lower=True, hermitian=True):
      """
      Helper function to extract the diagonal and triangular matrices for
      LDL.T factorization.
  
      Parameters
      ----------
      ldu : ndarray
          The compact output returned by the LAPACK routing
      pivs : ndarray
          The sanitized array of {0, 1, 2} denoting the sizes of the pivots. For
          every 2 there is a succeeding 0.
      lower : bool, optional
          If set to False, upper triangular part is considered.
      hermitian : bool, optional
          If set to False a symmetric complex array is assumed.
  
      Returns
      -------
      d : ndarray
          The block diagonal matrix.
      lu : ndarray
          The upper/lower triangular matrix
      """
      is_c = iscomplexobj(ldu)
      d = diag(diag(ldu))
      n = d.shape[0]
      blk_i = 0  # block index
  
      # row/column offsets for selecting sub-, super-diagonal
      x, y = (1, 0) if lower else (0, 1)
  
      lu = tril(ldu, -1) if lower else triu(ldu, 1)
      diag_inds = arange(n)
      lu[diag_inds, diag_inds] = 1
  
      for blk in pivs[pivs != 0]:
          # increment the block index and check for 2s
          # if 2 then copy the off diagonals depending on uplo
          inc = blk_i + blk
  
          if blk == 2:
              d[blk_i + x, blk_i + y] = ldu[blk_i + x, blk_i + y]
              # If Hermitian matrix is factorized, the cross-offdiagonal element
              # should be conjugated.
              if is_c and hermitian:
                  d[blk_i + y, blk_i + x] = ldu[
                      blk_i + x, blk_i + y
                  ].conj()
              else:
                  d[blk_i + y, blk_i + x] = ldu[blk_i + x, blk_i + y]
  
              lu[blk_i + x, blk_i + y] = 0.0
          blk_i = inc
  
      return d, lu
  
file_path: catboost/contrib/python/scipy/py3/scipy/linalg/_decomp_ldl.py
imports: from warnings import warn
  import numpy
  from numpy import atleast_2d, ComplexWarning, arange, zeros_like, imag, diag, iscomplexobj, tril, triu, argsort, empty_like
  from .decomp import _asarray_validated
  from .lapack import get_lapack_funcs, _compute_lwork
label_desc: Use image node_id 3 for calling a global function with example usage: _ldl_get_d_and_l(ldu, pivs, lower, hermitian) and returns: d,  lu