def _target(x):    
     x = np.asarray(x)
     theta = np.array((0.3, 0.7))
     p1 = standard_multivariate_normal_pdf(x-np.array(( mu,  mu)))
     p2 = standard_multivariate_normal_pdf(x-np.array((-mu, -mu)))
     return np.dot(theta, np.array((p1,p2)))
 def _target(x):    
     x = np.asarray(x)
     return standard_multivariate_normal_pdf(x-np.array(( mu,  mu)))