1. Purpose
-------
This directory contains example drivers that call subroutines
[s,d]sband.f, [s,d]nband.f or [c,z]nband.f to solve various eigenvalue
problems in which matrices have BANDED structure. These drivers illustrate
how to construct LAPACK-style banded matrices, and how to set various
ARPACK parameters to solve different problems in different modes. The
user may modify any one of these drivers, and construct his/her own matrix
to solve the problem of his/her own interest.
2. Naming convention
-----------------
The name for each banded solver has the form 'XYband.f', where
X - is 's' (single precision)
or 'd' (double precision)
or 'c' (single precision complex)
or 'z' (double precision complex)
Y - is 's' (symmetric)
or 'n' (nonsymmetric)
The name for each driver has the form 'XYbdrN.f', where
X - is 's' (single precision)
or 'd' (double precision)
or 'c' (single precision complex)
or 'z' (double precision complex)
Y - is 's' (symmetric)
or 'n' (nonsymmetric)
N - is a number between 1 and 6. If
N = 1, the driver solves a STANDARD eigenvalue problem in
REGULAR mode.
N = 2, the driver solves a STANDARD eigenvalue problem in
SHIFT-INVERT mode.
N = 3, the driver solves a GENERALIZED eigenvalue problem in
INVERSE mode.
N = 4, the driver solves a GENERALIZED eigenvalue problem in
SHIFT-INVERT mode (using mode 3 of __aupd.)
These are four commonly used drivers.
When N > 4 (only for real matrices), a special mode is used.
For symmetric problem, if
N = 5, the driver solves a GENERALIZED eigenvalue problem in
BUCKLING mode.
N = 6, the driver solves a GENERALIZED eigenvalue problem in
CAYLEY mode.
For nonsymmetric problem, if
N = 5, the driver solves a STANDARD eigenvalue problem in
SHIFT-INVERT mode using mode 4 of [d,s]naupd.f.
N = 6. the driver solves a GENERALIZED eigenvalue problem
SHIFT-INVERT mode using mode 4 of [d,s]naupd.f.
Note: the imaginary part of the shift MUST be nonzero when
these two drivers are used.
3. Usage
-----
To run these drivers, you may use the makefile in this
directory and issue, for example, "make snbdr1". Then
execute using "snbdr1".
