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/*
ARPACK++ v1.2 2/20/2000
c++ interface to ARPACK code.
MODULE LSMatrxC.h
Function template for the one dimensional discrete Laplacian
on the interval [0, 1], with zero Dirichlet boundary conditions.
The difference between the function shown here and SymmetricMatrixB
is only the scaling factor.
ARPACK Authors
Richard Lehoucq
Danny Sorensen
Chao Yang
Dept. of Computational & Applied Mathematics
Rice University
Houston, Texas
*/
#ifndef LSMATRXC_H
#define LSMATRXC_H
#include <math.h>
template<class ARFLOAT, class ARINT>
void SymmetricMatrixC(ARINT n, ARINT& nnz, ARFLOAT* &A,
ARINT* &irow, ARINT* &pcol, char uplo = 'L')
{
// Defining internal variables.
ARINT i, j;
ARFLOAT h, df, dd;
// Defining constants.
h = ARFLOAT(n+1);
dd = 2.0*h;
df = -h;
// Defining the number of nonzero elements in A.
nnz = 2*n-1;
// Creating output vectors.
A = new ARFLOAT[nnz];
irow = new ARINT[nnz];
pcol = new ARINT[n+1];
// Defining matrix A.
pcol[0] = 0;
i = 0;
if (uplo == 'U') {
for (j = 0; j < n; j++) {
if (j) {
A[i] = df; irow[i++] = j-1;
}
A[i] = dd; irow[i++] = j;
pcol[j+1] = i;
}
}
else {
for (j = 0; j < n; j++) {
A[i] = dd; irow[i++] = j;
if (n-j-1) {
A[i] = df; irow[i++] = j+1;
}
pcol[j+1] = i;
}
}
} // SymmetricMatrixC.
#endif // LSMATRXC_H
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