@Override public double calculate_K(int[] x_index,double[] x_att,int[] y_index,double[] y_att){
  double expression=norm2(x_index,x_att,y_index,y_att) / sigma;
  if (expression > 1) {
    return 0.0d;
  }
 else {
    double minus=1.0d - expression;
    return Math.pow(minus,degree);
  }
}

@ Override public double calculate_K ( int [ ] x_index , double [ ] x_att , int [ ] y_index , double [ ] y_att ) { double expression = norm2 ( x_index , x_att , y_index , y_att ) / sigma ; if ( expression > 1 ) { return 0.0d ; } else { double minus = 1.0d - expression ; return Math . pow ( minus , degree ) ; } }
calculates kernel value of vectors x and y .
