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<H2><A NAME="SECTION00045000000000000000"></A>
<A NAME="sec:prec"></A>
<BR>
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&nbsp;<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="714"></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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