HP MLIB User's Guide Vol. 2 7th Ed.

1012 HP MLIB User’s Guide
What you need to know to use these subprograms
Output controls
This package differs from most library subroutines in providing optional
printed or printable output. The amount of output is controlled by an integer
variable,
msglvl, specifying the message level. Setting msglvl ≤ 0 suppresses all
printed messages, including error messages, and thus should generally be
avoided. However, this will be the proper message level when the contents of
the output file must originate solely from the application program that is using
the sparse matrix package. When
msglvl = 1, a small amount of runtime
statistics, including matrix inertias necessary for interpreting discardable
results, and any error messages will be printed. When
msglvl > 1, the complete
set of runtime statistics will be printed. If msglvl ≥ 3, various arrays whose
length is on the order of the number of equations will be printed. If msglvl ≥ 4,
volumes of output will be produced for debugging purposes.
We recommend that you set msglvl = 1. The higher msglvl values (≥ 3) are
intended for debugging purposes and generate copious amounts of printed
output. Further, their use for this purpose may require some knowledge of the
data structures being used by the package.
Paths of control
This package provides both a single standard format for sparse matrices and a
completely general interface that allows the user to represent the sparse
matrices in the most convenient form for use outside this package. The possible
paths through the package are illustrated in Figure 15-3 and Figure 15-4.