func NewHeun(y *data.Synced, torqueFn func(bool) *data.Synced, postStep func(*data.Slice), dt, multiplier float64, time *float64) *Heun {
util.Argument(dt > 0 && multiplier > 0)
m := y.Mesh()
dy0 := NewSlice(3, m)
return &Heun{newSolverCommon(dt, multiplier, time), y, dy0, torqueFn, postStep}
}
