'alias ``reset``, set all state variables to initial values'

def initialize(self):

    N = self.N
    self.mean = array(self.x0, copy=True)
    self.sigma = self.sigma0
    self.sigmai = np.ones(N)
    self.ps = np.zeros(N)
    self.r = np.zeros(N)
    self.pr = 0
    self.sigma_r = 0
