Itsol is a library of iterative solvers for general sparse linear systems of equations. itsol can be viewed as an extension of the itsol module in sparskit. it is written in c and offers a selection of recently developed preconditioners. the preconditioner suite includes:

* iluk (ilu preconditioner with level of fill)
* ilut (ilu preconditioner with threshold)
* iluc (crout version of ilut)
* vbiluk (variable block preconditioner with level of fill - with automatic
block detection)
* vbilut (variable block preconditioner with threshold - with automatic
block detection)
* arms (algebraic recursive multilevel solvers -- includes actually several
methods - in particular the standard arms and the ddpq version which uses
nonsymmetric permutations)
note that itsol is a scalar package. you may find parallel implentations of some of the preconditioners listed above in parms.