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/*
ARPACK++ v1.2 2/20/2000
c++ interface to ARPACK code.
MODULE BNMatrxB.h
Function template for the stiffness matrix obtained from
the finite element discretization of the 1-dimensional
convection diffusion operator d^2u/dx^2 + rho*(du/dx) on
the interval [0,1] with zero Dirichlet boundary conditions
using linear elements.
ARPACK Authors
Richard Lehoucq
Danny Sorensen
Chao Yang
Dept. of Computational & Applied Mathematics
Rice University
Houston, Texas
*/
#ifndef BNMATRXB_H
#define BNMATRXB_H
template<class ARFLOAT, class ARINT>
void StiffnessMatrix(ARINT n, ARFLOAT rho, ARINT& nL, ARINT& nU, ARFLOAT* &A)
{
ARINT i;
ARFLOAT dd, dl, du, h;
// Defining constants.
h = 1.0/ARFLOAT(n+1);
dd = 2.0/h;
dl = -1.0/h - 0.5*rho;
du = -1.0/h + 0.5*rho;
// Defining the lower and the upper bandwidth.
nL = 1;
nU = 1;
// Creating output vector A.
A = new ARFLOAT[3*n];
for (i=1; i<(3*n); i+=3) {
if (i-1) A[i-1] = du;
A[i] = dd;
if (n-i-1) A[i+1] = dl;
}
} // StiffnessMatrix.
#endif // BNMATRXB_H
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