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/*
ARPACK++ v1.0 8/1/1997
c++ interface to ARPACK code.
MODULE LNMatrxV.h
Function template that generates a sparse (2n x n) retangular matrix.
ARPACK Authors
Richard Lehoucq
Danny Sorensen
Chao Yang
Dept. of Computational & Applied Mathematics
Rice University
Houston, Texas
*/
#ifndef LNMATRXV_H
#define LNMATRXV_H
template<class FLOAT, class INT>
void RetangularMatrix(INT n, INT& m, INT& nnz, FLOAT* &A,
INT* &irow, INT* &pcol)
{
INT i, j;
FLOAT dd, dl, du;
// Defining constants.
dl = 1.0;
dd = 4.0;
du = 2.0;
// Defining the number of nonzero elements and lines of the matrix.
nnz = n*6-2;
m = n*2;
// Creating output vectors.
A = new FLOAT[nnz];
irow = new INT[nnz];
pcol = new INT[n+1];
// Filling A, irow and pcol.
pcol[0] = 0;
j = 0;
for (i=0; i!=n; i++) {
if (i != 0) {
irow[j] = i-1;
A[j++] = du;
}
irow[j] = i;
A[j++] = dd;
irow[j] = i+1;
A[j++] = dl;
irow[j] = i+n-1;
A[j++] = dl;
irow[j] = i+n;
A[j++] = dd;
if (i != (n-1)) {
irow[j] = i+n+1;
A[j++] = du;
}
pcol[i+1] = j;
}
} // Retangular matrix.
#endif // LNMATRXV_H
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