/*
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 * and open the template in the editor.
 */
package polynomial;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.text.DecimalFormat;
import java.util.Scanner;

/**
 *
 * @author casey
 */
public class Polynomial {


    public static void main(String[] args) throws FileNotFoundException {

        Scanner read = new Scanner(new BufferedReader(new FileReader("poly.txt")));

            //first line into x array
            String line = read.nextLine();
            System.out.println("LINE: "+line);
            String[] x = line.split("\\s+");

            //second line into y array
            line = read.nextLine();
            System.out.println("LINE: "+line);
            String[] y = line.split("\\s+");

        read.close();

        Double[][] array = new Double[(x.length)*2][y.length+1];

        for(int i = 0; i<x.length*2;i++){
            for(int j = 0;j<array[0].length;j++){
                array[i][j] = 0.0;
            }
        }

        DecimalFormat df = new DecimalFormat("###.###");
         int a = 0;

        for(int i = 0; i<(x.length*2); i=i+2){

            array[i][0] = Double.parseDouble(x[a]);
            a++;

        }
        a=0;
        for(int j = 0; j<(y.length*2); j=j+2){
            array[j][1] = Double.parseDouble(y[a]);
            a++;

        }

        //LAGRANGES METHODS
        /*System.out.println("x: ");
        for(int i=0; i<x.length;i++){
            System.out.print(x[i]+ "\t");
        }
        System.out.println("\ny: ");
        for(int i=0; i<y.length;i++){
            System.out.print(y[i]+ "\t");
        }
        System.out.println();

        System.out.println("l_0");
        int c = 0;
        Double[] denominator = new Double[x.length];
        int[] values = new int[x.length];
        for(int i = 0; i<x.length;i++){
            values[i] = i;
        }

        for(int i = 0; i<1; i++){
        denominator[i] = ((Double.parseDouble(x[c]) - Double.parseDouble(x[c+1])) * (Double.parseDouble(x[c]) - Double.parseDouble(x[c+2]))
                 * (Double.parseDouble(x[c]) - Double.parseDouble(x[c+3])));
        }
        System.out.println("Denominator: "+denominator[0]);*/

        //DIVIDED METHOD


        System.out.println("x\t"+"f[]\t"+"f[,]\t"+"f[,,]\t"+"f[,,,]");


        int i = 0;
        for(int j=2; j<x.length-1;j++ ){
          for(i = 0; i <2*(x.length-1); i=i+2){
            array[i+1][j] = (((array[i+2][j-1]) - (array[i][j-1])) /((array[i+j][0]) - (array[i][0])));
            System.out.println("i+j: "+(i+j));
          }
           System.out.println("i: "+i);
        }




       //i=6;
       //j=0;
           // array[i-2][j+3] = ((array[i-1][j+2]) - (array[i-3][j+2])) /((array[i][j]) - (array[i-4][j]));
           // array[i-4][j+3] = ((array[i-3][j+2]) - (array[i-5][j+2])) /((array[i-2][j]) - (array[i-6][j]));
            //array[i-3][j+4] = ((array[i-2][j+3]) - (array[i-4][j+3])) /((array[i][j]) - (array[i-6][j]));



        for(int s = 0; s<x.length*2; s++){
            for(int t = 0; t<y.length+1; t++){
                //System.out.println("Piece: "+df.format(array[0][0]));
                 System.out.print((array[s][t])+"\t");
            }

            System.out.println();
        }


        String polynomial = String.valueOf(df.format(array[0][1]));
        String xValue ="";
        int j = 1;
        int count = 0;
        for(int I=0; I<x.length-1;I++){
            xValue = xValue+"(x-"+x[count]+")";

            count++;
            System.out.println("Before i: "+I+" j: "+j);

            polynomial = polynomial + " + " + array[I+1][j+1]+ xValue;
            j++;
        }
        System.out.println("Interpolating polynimal is:");
        System.out.println(polynomial);

    }



}