1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
|
/*
ARPACK++ v1.0 8/1/1997
c++ interface to ARPACK code.
MODULE DNSymReg.cc.
Example program that illustrates how to solve a real
nonsymmetric dense standard eigenvalue problem in regular
mode using the ARluNonSymStdEig class.
1) Problem description:
In this example we try to solve A*x = x*lambda in regular mode,
where A is derived from the standard central difference
discretization of the 2-dimensional convection-diffusion operator
(Laplacian u) + rho*(du/dx)
on a unit square with zero Dirichlet boundary conditions.
2) Data structure used to represent matrix A:
Although A is very sparse in this example, it is stored
here columnwise as a dense matrix.
3) Included header files:
File Contents
----------- -------------------------------------------
dnmatrxa.h DenseMatrixA, a function that generates
matrix A.
ardnsmat.h The ARdsNonSymMatrix class definition.
ardsnsym.h The ARluNonSymStdEig class definition.
lnsymsol.h The Solution function.
4) ARPACK Authors:
Richard Lehoucq
Kristyn Maschhoff
Danny Sorensen
Chao Yang
Dept. of Computational & Applied Mathematics
Rice University
Houston, Texas
*/
#include "dnmatrxa.h"
#include "ardnsmat.h"
#include "ardsnsym.h"
#include "lnsymsol.h"
main()
{
// Defining variables;
int nx;
int n; // Dimension of the problem.
double rho; // Parameter used to define A.
double* A; // Pointer to an array that stores the elements of A.
// Creating a 100x100 matrix.
nx = 10;
rho = 100.0;
DenseMatrixA(nx, rho, n, A);
ARdsNonSymMatrix<double> matrix(n, A);
// Defining what we need: the four eigenvectors of A with largest magnitude.
ARluNonSymStdEig<double> dprob(4, matrix, "SM", 20);
// Finding eigenvalues and eigenvectors.
dprob.FindEigenvectors();
// Printing solution.
Solution(matrix, dprob);
} // main.
|
