code: private void acceptNewState( double fx_candidate ) {
  		DMatrixRMaj tmp = x;
  		x = x_next;
  		x_next = tmp;
  
  		fx = fx_candidate;
  
  		mode = Mode.COMPUTE_DERIVATIVES;
  	}
docs: The new state has been accepted. Switch the internal state over to this
  @param fx_candidate The new state