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/*
ARPACK++ v1.2 2/20/2000
c++ interface to ARPACK code.
MODULE LNMatrxV.h
Function template that generates a sparse (2n x n) rectangular 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 ARFLOAT, class ARINT>
void RectangularMatrix(ARINT n, ARINT& m, ARINT& nnz, ARFLOAT* &A,
ARINT* &irow, ARINT* &pcol)
{
ARINT i, j;
ARFLOAT 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 ARFLOAT[nnz];
irow = new ARINT[nnz];
pcol = new ARINT[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;
}
} // Rectangular matrix.
#endif // LNMATRXV_H
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