// Core integrator for DOP853
public double Integrate(ref double t, ref double dt, double[] x, ref int step, int nmax, double posneg, bool dense)
{
double th = t, err = 0;
// Basic integration step
while (step < nmax)
{
Step(t, dt, x);
step++;
th = t + dt;
// Error estimation
err = Error(dt, x);
dtold = dt;
told = t;
// Computation of HNEW
if (controller.Success(err, posneg, ref dt))
{
break;
}
}
fcn(th, xout, k4);
// Stiffness detection
if (!stiff.Check(controller.Accepted, dtold, k4, k3, xout, xtemp))
{
throw new Exception(" The problem seems to become stiff at t = " + t);
}
if (dense)
{
PrepareInterpolation(t, dtold, x);
}
for (int i = 0; i < n; ++i)
{
dxdt[i] = k4[i];
x[i] = xout[i];
}
t = th;
return(err);
}
