class_docstr: IterOpInv:
     helper class to repeatedly solve [A-sigma*M]*x = b
     using an iterative method
code: def dtype(self):
      return self.OP.dtype
  
imports: from .None import _arpack
  import numpy
  import warnings
  from scipy.sparse.linalg.interface import aslinearoperator, LinearOperator
  from scipy.sparse import eye, issparse, isspmatrix, isspmatrix_csr
  from scipy.linalg import eig, eigh, lu_factor, lu_solve
  from scipy.sparse.sputils import isdense, is_pydata_spmatrix
  from scipy.sparse.linalg import gmres, splu
  from scipy.sparse.linalg.eigen.lobpcg import lobpcg
  from scipy._lib._util import _aligned_zeros
  from scipy._lib._threadsafety import ReentrancyLock
label_desc: Use image node_id 3 for calling the IterOpInv obj's underlying member method code with example usage: obj.dtype() and returns: self