@Override public double driftDiscretization(final StochasticProcess1D sp,final double t0,final double x0,final double dt){
  return sp.drift(t0,x0) * dt;
}

@ Override public double driftDiscretization ( final StochasticProcess1D sp , final double t0 , final double x0 , final double dt ) { return sp . drift ( t0 , x0 ) * dt ; }
returns an approximation of the drift defined as < p > \ mu ( t_0 , x_0 ) \ delta t
