(sums, square, count)
return mean, var
compute global feature mean and variance
     vars = E(x^2) - (E(x))^2
compute global feature mean and variance
     vars = E(x^2) - (E(x))^2
compute global feature mean and variance vars = E ( x^2 ) - ( E ( x )) ^2
def compute_cmvn(sums, square, count):
  ''' compute global feature mean and variance
     vars = E(x^2) - (E(x))^2
  '''
  mean = sums / count
  var = (square / count) - np.square(mean)
  return mean, var
def compute_cmvn ( sums , square , count ) : mean = sums / count var = ( square / count ) - np . square ( mean ) return mean , var