Linear Solvers in LinearPDE

Currently esys.finley supports the linear solvers LinearPDE.PCG , LinearPDE.GMRES , LinearPDE.PRES20 and LinearPDE.BICGSTAB . For LinearPDE.GMRES the options trancation and restart of the getSolution can be used to control the trunction and restart during iteration. Default values are truncation=5 and restart=20. The default solver is LinearPDE.BICGSTAB but if the symmetry flag is set LinearPDE.PCG is the default solver. esys.finley supports the solver options iter_max which specifies the maximum number of iterations steps, verbose=True or False and preconditioner=JACOBI or ILU0. In some installations esys.finley supports the LinearPDE.DIRECT solver and the solver options reordering=util.NO_REORDERING, util.MINIMUM_FILL_IN or util.NESTED_DISSECTION (default is util.NO_REORDERING), drop_tolerance specifying the threshold for values to be dropped in the incomplete elimation process (default is 0.01) and drop_storage specifying the maximum increase in storage allowed in the incomplete elimation process (default is 1.20).