public FLS_Timestepper_AB(FourierLevSetControl Control, double[] currentState, DelComputeChangerate _DelCompChange, DelEvolveFourier _DelEvolveFourier, int ABorder)
: base(Control, currentState, _DelCompChange, _DelEvolveFourier)
{
ABsc_chain = new ABSchemeCoeff[ABorder];
for (int i = 0; i < ABorder; i++)
{
ABsc_chain[i] = ABSchemeCoeff.AB(i + 1);
}
}
/// <summary>
/// returns the coefficients for a AdamsBashforth scheme of order <paramref name="order"/>.
/// </summary>
/// <param name="order"></param>
static public ABSchemeCoeff AB(int order)
{
ABSchemeCoeff ABsc = new ABSchemeCoeff();
switch (order)
{
case 1: {
ABsc.coeffs = new double[] { 1.0 };
break;
}
case 2: {
ABsc.coeffs = new double[] { 3.0 / 2.0, -1.0 / 2.0 };
break;
}
case 3: {
ABsc.coeffs = new double[] { 23.0 / 12.0, -4.0 / 3.0, 5.0 / 12.0 };
break;
}
case 4: {
ABsc.coeffs = new double[] { 55.0 / 24.0, -59.0 / 24.0, 37.0 / 24.0, -3.0 / 8.0 };
break;
}
default:
throw new NotImplementedException("AB scheme of order " + order + " is not supported.");
}
if (Math.Abs(ABsc.coeffs.Sum() - 1.0) > 1.0e-10)
{
throw new ApplicationException();
}
return(ABsc);
}
