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/*
ARPACK++ v1.0 8/1/1997
c++ interface to ARPACK code.
MODULE BSymGCay.cc.
Example program that illustrates how to solve a real
symmetric generalized eigenvalue problem in Cayley mode
using the ARluSymGenEig class.
1) Problem description:
In this example we try to solve A*x = B*x*lambda in Cayley
mode, where A is the one dimensional discrete Laplacian on
the interval [0, 1], with zero Dirichlet boundary conditions,
and B is the mass matrix formed by using piecewise linear
elements on [0, 1].
2) Data structure used to represent matrices A and B:
{nsdiag, A}: matrix A data in symmetric band format. The elements
of the main diagonal and the first nsdiag subdiagonals of A are
stored sequentially, by columns, in vector A.
{nsdiag, B}: matrix B in band format.
3) Library called by this example:
The LAPACK package is called by ARluSymGenEig to solve
some linear systems involving (A-sigma*B).
4) Included header files:
File Contents
----------- -------------------------------------------
bsmatrxb.h BandMatrixB, a function that generates
matrix A in band format.
bsmatrxc.h BandMatrixC, a function that generates
matrix B in band format.
arbsmat.h The ARbdSymMatrix class definition.
arbgsym.h The ARluSymGenEig class definition.
lsymsol.h The Solution function.
5) ARPACK Authors:
Richard Lehoucq
Kristyn Maschhoff
Danny Sorensen
Chao Yang
Dept. of Computational & Applied Mathematics
Rice University
Houston, Texas
*/
#include "bsmatrxb.h"
#include "bsmatrxc.h"
#include "arbsmat.h"
#include "arbgsym.h"
#include "lsymsol.h"
main()
{
// Defining variables;
int n; // Dimension of the problem.
int nsdiag; // Lower (and upper) bandwidth of A (and B).
double* valA; // pointer to an array that stores the elements of A.
double* valB; // pointer to an array that stores the elements of B.
// Creating matrices A and B.
n = 100;
BandMatrixB(n, nsdiag, valA);
ARbdSymMatrix<double> A(n, nsdiag, valA);
BandMatrixC(n, nsdiag, valB);
ARbdSymMatrix<double> B(n, nsdiag, valB);
// Defining what we need: the four eigenvectors nearest to 150.0.
ARluSymGenEig<double> dprob('C', 4L, A, B, 150.0);
// Finding eigenvalues and eigenvectors.
dprob.FindEigenvectors();
// Printing solution.
Solution(A, B, dprob);
} // main.
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