code: public static double process_F64(double sample, double x[], double y[], int i0, int i1) {
  		double result = 0;
  
  		for (int i = i0; i <= i1; i++) {
  			double numerator = 1.0;
  
  			for (int j = i0; j <= i1; j++) {
  				if (i != j)
  					numerator *= sample - x[j];
  			}
  
  			double denominator = 1.0;
  
  			double a = x[i];
  
  			for (int j = i0; j <= i1; j++) {
  				if (i != j)
  					denominator *= a - x[j];
  			}
  
  			result += (numerator / denominator) * y[i];
  		}
  
  		return result;
  	}
docs: UsingLlangrange's formula it interpulates the value of a function at the specified sample
  point given discrete samples.  Which samples are used and the order of the approximation are
  given by i0 and i1.
  
  @param sample Where the estimate is done.
  @param x	  Where the function was sampled.
  @param y	  The function's value at the sample points
  @param i0	 The first point considered.
  @param i1	 The last point considered.
  @return The estimated y value at the sample point.