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

1032 HP MLIB User’s Guide
DSEVES Eigenextraction
lfinit If .TRUE., the value of the argument lftend is to be
used as a restriction on the location of computed
eigenvalues. If .FALSE., no lower bound is placed on
the value of computed eigenvalues; equivalently, the
left endpoint is negative infinity.
lftend Left endpoint of an interval in which the desired
eigenvalues lie; not used if lfinit is .FALSE.
rfinit If .TRUE., the value of the argument rhtend is to be
used as a restriction on the location of computed
eigenvalues. If .FALSE., no upper bound is placed on
the value of computed eigenvalues; equivalently, the
right endpoint is positive infinity.
rhtend Right endpoint of an interval in which the desired
eigenvalues lie; not used if rfinit is .FALSE.
center A center or critical value for use when eigenvalues
nearest some particular value are desired. Referenced
only when which specifies ’centered’ or ’nearest’.
Updated global Global communications array for this problem. This
array must be passed, untouched by the user, to
successive subroutines in this package.
Output nfound The number of eigenvalues computed and confirmed to
meet the problem description constraints by inertia
(Sturm sequence) computations.
ndiscd The number of other eigenvalues computed during the
course of the computation but discarded because they
were outside specifications for eigenvalues or because
they were not confirmed by inertia computations.
ier Status response:
ier = 0 Normal return.
ier < 0 Fatal error, no useful results returned.
ier > 0 Fatal error, but some eigenvalues and
vectors computed.
ier = −700 DSEVEX called without first
successfully calling earlier stages.
ier = ±701 Error in storage allocation.
ier = ±702 Illegal specification for lftend and
rhtend.