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##

Software Availability

A FORTRAN implementation of the non-Hermitian Lanczos procedure
with look-ahead
to cure breakdowns is available in QMRPACK [180].
The corresponding routine names are `DULAL` for double precision
real and `ZULAL` for double precision complex.
These routines first run the look-ahead Lanczos algorithm without
re-biorthogonalization for a
number of steps. They will then prompt the user for the number of
eigenvalues to compute. In addition, the routine will also find
the common eigenvalues in two successive runs for
the identification test as described at the step (16) of
Algorithm 7.13.

A set of MATLAB routines for implementing the adaptive block Lanczos method
(ABLE) described in §7.9 can be used to implement
Algorithm 7.13 by defining the block size as one
at the initial step. Optional re-biorthogonalization schemes are available.
An adaptive block size scheme is used for the treatment of (near) breakdown
and/or multiple or closely clustered eigenvalues of interest.

For more information about this software, including how to access it,
see the book's homepage, ETHOME.

** Next:** Notes and References
** Up:** Lanczos Method Z. Bai
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Susan Blackford
2000-11-20