@Override public double calculateDistance(double[] x1,double[] x2){
  return Math.sqrt((norm2(x1,x2) / sigma) + (shift * shift));
}

@ Override public double calculateDistance ( double [ ] x1 , double [ ] x2 ) { return Math . sqrt ( ( norm2 ( x1 , x2 ) / sigma ) + ( shift * shift ) ) ; }
calculates kernel value of vectors x and y .
