Workspace Requirements

For storage of certain intermediate results, the solution modules require a real vector WKSP(*) and a corresponding variable NW indicating the available space. The length of the workspace array varies with each solution module and the maximum amount needed is given in the following table.

Solution Module	Maximum Length of WKSP(*)
JCG()	${\bf 4*N + 4*ITMAX}$
JSI()	${\bf 2*N}$
SOR()	${\bf 2*N}$
SSORCG()	${\bf 6*N + 4*ITMAX}$
SSORSI()	${\bf 5*N}$
RSCG()	${\bf N + 3*NB + 4*ITMAX}$
RSSI()	${\bf N + NB}$

where N is the number of linear equations, NB is the number of black grid points in the red-black ordering, and ITMAX is the maximum number of iterations allowed. The Conjugate Gradient routines require ${\bf 4*ITMAX}$ extra storage locations for eigenvalue calculations. It should be noted that the actual amount of workspace used may be somewhat less than these upper limits since some of the latter are dependent on the maximum number of iterations allowed, ITMAX, stored in IPARM(1). Clearly, the array WKSP(*) must be dimensioned to at least the value of NW.