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/*
ARPACK++ v1.2 2/18/2000
c++ interface to ARPACK code.
MODULE DSymGReg.cc.
Example program that illustrates how to solve a real symmetric
dense generalized eigenvalue problem in regular mode using the
ARluSymGenEig class.
1) Problem description:
In this example we try to solve A*x = B*x*lambda in regular
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:
Although A and B are very sparse in this example, they are
stored here as dense symmetric matrices. The lower triangular
part of A snd B is stored, by columns, in vectors A and B.
3) Library called by this example:
The LAPACK package is called by ARluSymGenEig to solve
some linear systems involving B.
4) Included header files:
File Contents
----------- -------------------------------------------
dsmatrxb.h DenseMatrixB, a function that generates
matrix A.
dsmatrxc.h DeseMatrixC, a function that generates
matrix B.
ardsmat.h The ARdsSymMatrix class definition.
ardgsym.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 "dsmatrxb.h"
#include "dsmatrxc.h"
#include "ardsmat.h"
#include "ardgsym.h"
#include "lsymsol.h"
int main()
{
// Defining variables;
int n; // Dimension of the problem.
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;
DenseMatrixB(n, valA);
ARdsSymMatrix<double> A(n, valA);
DenseMatrixC(n, valB);
ARdsSymMatrix<double> B(n, valB);
// Defining what we need: the four eigenvectors with largest magnitude.
ARluSymGenEig<double> dprob(4L, A, B);
// Finding eigenvalues and eigenvectors.
dprob.FindEigenvectors();
// Printing solution.
Solution(A, B, dprob);
} // main.
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