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<H2><A NAME="SECTION00044000000000000000"></A>
<A NAME="sec:prec"></A>
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Preconditioner data structure
</H2>
Our base library offers support for simple well known preconditioners
like Diagonal Scaling or Block Jacobi with incomplete
factorization ILU(0).
<P>
A preconditioner is held in the precdata<TT> psb_prec_type</TT> data structure reported in
figure <A HREF="#fig:prectype">6</A>. The <code>psb_prec_type</code>
data type may contain a simple preconditioning matrix with the
associated communication descriptor.The internal preconditioner is allocated appropriately with the
dynamic type corresponding to the desired preconditioner.
<DIV ALIGN="CENTER"><A NAME="fig:prectype"></A><A NAME="866"></A>
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<CAPTION ALIGN="BOTTOM"><STRONG>Figure 6:</STRONG>
The PSBLAS defined data type that contains a preconditioner.</CAPTION>
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<PRE>
type psb_Tprec_type
class(psb_T_base_prec_type), allocatable :: prec
end type psb_Tprec_type
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