** This is part of the CTSim program
** Copyright (c) 1983-2001 Kevin Rosenberg
**
-** $Id: cubicinterp.cpp,v 1.2 2001/02/09 01:55:24 kevin Exp $
+** $Id: cubicinterp.cpp,v 1.3 2001/02/09 14:34:16 kevin Exp $
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License (version 2) as
CubicInterpolator::CubicInterpolator (const double* const y, const int n)
: m_pdY(y), m_n(n)
{
+ // Precalculate 2nd derivative of y and put in m_pdY2
+ // Calculated by solving set of simultaneous cubic spline equations
+ // Only n-2 cubic spline equations, but able to make two more
+ // equations by setting second derivative to 0 at ends
+
m_pdY2 = new double [n];
m_pdY2[0] = 0; // second deriviative = 0 at beginning and end
m_pdY2[n-1] = 0;