>> help deflation
 
   This function is an auxiliary routine that is used to check for deflation
   and if necessary, to perform the deflation.  It is called in the functions
   "band_Arnoldi", "band_Lanczos", "sym_band_Lanczos", "Herm_band_Lanczos",
   "Jsym_band_Lanczos", and "JHerm_band_Lanczos".
 
   The input flag "vw_f" is used to produce correct display messages:
 
   vw_f = 0   means that there is only one type of Krylov vectors (as in 
              "band_Arnoldi", "Herm_band_Lanczos", "sym_band_Lanczos",
              "Jsym_band_Lanczos", "JHerm_band_Lanczos")
 
   vw_f = 1   means that right Krylov vectors are deflated
 
   vw_f = -1  means that left Krylov vectors are deflated
 
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   BANDITS: a Matlab Package of Band Krylov Subspace Iterations
 
   Copyright (c) 2018-2019 Roland W. Freund
   See LICENSE.txt for license
 
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