public void ComputeLamda(Particle particle){
		List<Particle> neighbours = particle.getNeighbours();
		float sumGradient = 0;
		for(Particle neighbour:neighbours){
			Vector3D grad = ComputeGrandientC(particle, neighbour);
			sumGradient += grad.LengthSquare();
		}
		//System.out.println("constraint = " + particle.getConstraint() + "\tsumgradient = " + sumGradient);
		particle.setLamda(particle.getConstraint() / (sumGradient + 10f) * -1);
	}