To illustrate usage of the package, the top-level calling sequence for PCG is given below:
CALL _PCG (IJOB,_<precon>,_<meth>,IA,JA,A,U,UEXACT,B,IWK,FWK,IPARM,FPARM,IER)
where
``_'' is either S, D, C or Z depending
on whether single/double precision or real/complex arithmetic is desired;
IJOB specifies the requested task such as the solution of single or
multiple systems;
<precon> and <meth> denote externally-defined
preconditioner and iterative method names;
IA, JA and A store the matrix ;
U, UEXACT and B store the approximate solution,
(optional) true solution and right hand side vectors;
IWK and FWK denote integer and floating point workspace;
IPARM and FPARM are parameter arrays; and,
IER is the error code.