class_docstr: IterOpInv:
     helper class to repeatedly solve [A-sigma*M]*x = b
     using an iterative method
class_docstr_tok: ["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 scipy.sparse.linalg.eigen.arpack import _arpack
  import numpy
  from scipy.sparse.linalg.interface import aslinearoperator, LinearOperator
  from scipy.sparse import identity, isspmatrix, isspmatrix_csr
  from scipy.linalg import lu_factor, lu_solve
  from scipy.sparse.sputils import isdense
  from scipy.sparse.linalg import gmres, splu
  import scipy
  import functools
  import operator
  from distutils.version import LooseVersion
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