message: Correct startup of integrators
diff: @@ -863,17 +863,12 @@ void NewmarkSolver::Step(Vector &x, Vector &dxdt, double &t, double &dt)
  double fac3 = beta;
  double fac4 = gamma;
  - // In the first pass d2xdt2 is not yet computed. If parameter choices requires
  - // d2xdt2 backward euler is used instead for the first step only.
  - if (first && !(fac0*fac2 == 0.0))
  - {
  - fac0 = 0.0;
  - fac2 = 0.0;
  - fac3 = 0.5;
  - fac4 = 1.0;
  + // In the first pass compute d2xdt2 directy from operator.
  + if (first)
  + {
  + f->Mult(x, dxdt, d2xdt2);
  first = false;
  }
  -
  f->SetTime(t + dt);
  x.Add(dt, dxdt);
  @@ -938,20 +933,14 @@ void GeneralizedAlpha2Solver::Step(Vector &x, Vector &dxdt,
  double fac4 = gamma*alpha_f/alpha_m;
  double fac5 = alpha_m;
  - // In the first pass d2xdt2 is not yet computed.
  - // If parameter choices requires d2xdt2 then
  - // Midpoint is used instead for the first step only.
  - if (first && (fac0 != 0.0) && (fac2 != 0.0))
  - {
  - fac0 = 0.0;
  - fac1 = 1.0;
  - fac2 = 0.0;
  - fac3 = 0.5;
  - fac4 = 1.0;
  - fac5 = 1.0;
  + // In the first pass compute d2xdt2 directy from operator.
  + if (first)
  + {
  + f->Mult(x, dxdt, d2xdt2);
  first = false;
  }
  +
  // Predict alpha levels
  add(dxdt, fac0*dt, d2xdt2, va);
  add(x, fac1*dt, va, xa);
  