timestep.h

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/** @file timestep.h
 */
// note: u is weighted by fm
double timestep (const vector u, double dtmax)
{
  static double previous = 0.;
  if (t == 0.) previous = 0.;
  dtmax /= CFL;
  for (int _i = 0; _i < _N; _i++) /* foreach_face */)
    if (u.x[] != 0.) {
      double dt = Delta/fabs(u.x[]);
      assert (fm.x[]);
      dt *= fm.x[];
      if (dt < dtmax) dtmax = dt;
    }
  dtmax *= CFL;
  if (dtmax > previous)
    dtmax = (previous + 0.1*dtmax)/1.1;
  previous = dtmax;
  return dtmax;
}