using System;
using System.Collections.Generic;
using System.Text;
using RungeKutta.Integrators;

namespace RungeKutta.SimStep
{
    /// <summary>
    /// Exactly the same thing as Verlet, except it takes a smaller window to sample velocity
    /// </summary>
    class VerletTweak : SimStepper
    {
        public State Integrate(State oldState, float timeStep, ODEs.ODE ode)
        {
            return Integrate(oldState, timeStep, ode.EvaluateForceAtState(oldState));
        }

        public State Integrate(State oldState, float timeStep, float acceleration)
        {
            oldState = new Verlet().Integrate(oldState, timeStep, acceleration);
            oldState.velocity = Derivator.MeanValueTheoremStep.Derivate(oldState.prevPos, -timeStep, oldState.position, 0);
            return oldState;
        }

        public int ForceEvaluations
        {
            get
            {
                return 1;
            }
        }

        public override string ToString()
        {
            return "Verlet Tweak";
        }
    }
}