| The Iteration object calculates whether the solution has reached the
  desired accuracy, or whether the maximum number of iterations has
  been reached. The method finished() checks both convergence and
  number of iterations. The method converged() only checks
  convergence. The error code() method is used to determine the return
  value for the this iterative solver function. The first() method is
  used to determine the first iteration of the loop. 
   
  For all algorithms, if the error_code() is 0, it suggests the algorithm 
  converges. Otherwise, if the error_code() returns 1, it means the maximum 
  number of iteration has been reached but the desired accuacy is not reached.
  For other return codes, see the respective document.
 |