Curve fitting - 2nd degree polynomial

package regression2;

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Functions
{
    public void printMatrix(double[][] matrix,int n)
    {
        for(int i=1;i<=n;i++)
        {
            for(int j=1;j<=n+1;j++)
            {
                System.out.print(matrix[i][j]+"\t");
            }
            System.out.println("");
        }
    }
    public void printList(List<Double> list)
    {
        int listSize = list.size();

        for(int i=0;i<listSize;i++)
        {
            System.out.println("Item "+(i+1)+" : "+list.get(i));
        }
    }
    public void printList(String listName,List<Double> list)
    {
        int listSize = list.size();
        System.out.println("In "+listName+" : ");
        for(int i=0;i<listSize;i++)
        {
            System.out.println("Item "+(i+1)+" : "+list.get(i));
        }
    }
    public double sumOfList(List<Double> list)
    {
        int listSize = list.size();
        double sum = 0;
        for(int i=0;i<listSize;i++)
        {
            sum=sum+list.get(i);
        }
        return sum;
    }
    public List<Double> makeSumOfSquareList(List<Double> list)
    {
        List<Double> newList = new ArrayList();
        int listSize = list.size();
        for(int i=0;i<listSize;i++)
        {
            double x = list.get(i);
            double newX = Math.pow(x,2);
            newList.add(newX);
        }
        return newList;
    }
    public List<Double> makeSumOfCubeList(List<Double> list)
    {
        List<Double> newList = new ArrayList();
        int listSize = list.size();
        for(int i=0;i<listSize;i++)
        {
            double x = list.get(i);
            double newX = Math.pow(x,3);
            newList.add(newX);
        }
        return newList;
    }
    public List<Double> makeSumOfPower4List(List<Double> list)
    {
        List<Double> newList = new ArrayList();
        int listSize = list.size();
        for(int i=0;i<listSize;i++)
        {
            double x = list.get(i);
            double newX = Math.pow(x,4);
            newList.add(newX);
        }
        return newList;
    }
    public List<Double> makeSumOfYXList(List<Double> listX,List<Double> listY)
    {
        List<Double> newList = new ArrayList();
        int listSize = listX.size();
        for(int i=0;i<listSize;i++)
        {
            double x = listX.get(i);
            double y = listY.get(i);
            double w = y*x;
            newList.add(w);
        }
        return newList;
    }
    public List<Double> makeSumOfYXSquareList(List<Double> listX,List<Double> listY)
    {
        List<Double> newList = new ArrayList();
        int listSize = listX.size();
        for(int i=0;i<listSize;i++)
        {
            double x = Math.pow(listX.get(i),2);
            double y = listY.get(i);
            double w = y*x;
            newList.add(w);
        }
        return newList;
    }
    public double[][] makeMatrix(List<Double> listX,List<Double> listY,int n)
    {
        double[][] x = new double[n+1][n+2];

        x[1][1]=n;
        x[1][2]=sumOfList(listX);
        x[1][3]=sumOfList(makeSumOfSquareList(listX));
        x[1][4]=sumOfList(listY);
        x[2][1]=sumOfList(listX);
        x[2][2]=sumOfList(makeSumOfSquareList(listX));
        x[2][3]=sumOfList(makeSumOfCubeList(listX));
        x[2][4]=sumOfList(makeSumOfYXList(listX,listY));
        x[3][1]=sumOfList(makeSumOfSquareList(listX));
        x[3][2]=sumOfList(makeSumOfCubeList(listX));
        x[3][3]=sumOfList(makeSumOfPower4List(listX));
        x[3][4]=sumOfList(makeSumOfYXSquareList(listX,listY));

        for(int i=1;i<=3;i++)
        {
            for(int j=1;j<=4;j++)
            {
                System.out.print(x[i][j]+"\t");
            }
            System.out.println("");
        }

        return x;
    }
    public List<Double> solutionGJM(double[][] matrix,int n)
    {
        List<Double> list = new ArrayList();
        double Matrix[][] = matrix;
        double pivotSafe=0,pivotOwn=0;
        for(int k=1;k<=n;k++)
        {

            for(int i=1;i<=n;i++)
            {
                if(i!=k)
                {
                    pivotSafe = Matrix[k][k];
                    pivotOwn = Matrix[i][k];
                    for(int j=1;j<=n+1;j++)
                    {
                        Matrix[i][j]=(pivotSafe*Matrix[i][j])-(pivotOwn*Matrix[k][j]);
                    }
                }
            }
        }
        //printMatrix(Matrix,n);
            for(int i=1;i<=n;i++)
            {
                double pivot = Matrix[i][i];
                    for(int j=1;j<=n+1;j++)
                    {
                        Matrix[i][j]=Matrix[i][j]/pivot;
                    }
            }

          //  printMatrix(Matrix,n);
          for(int i = 1;i<=n;i++)
          {
              list.add(Matrix[i][n+1]);
          }
        return list;
    }
    /*
    public double[][] elimination1(double[][] matrix,int n)
    {
        double Matrix[][] = matrix;
        double pivotSafe=0,pivotOwn=0;
        for(int k=1;k<=n;k++)
        {

            for(int i=1;i<=n;i++)
            {
                if(i!=k)
                {
                    pivotSafe = Matrix[k][k];
                    pivotOwn = Matrix[i][k];
                    for(int j=1;j<=n+1;j++)
                    {
                        Matrix[i][j]=(pivotSafe*Matrix[i][j])-(pivotOwn*Matrix[k][j]);
                    }
                }
            }
        }
        //printMatrix(Matrix,n);
            for(int i=1;i<=n;i++)
            {
                double pivot = Matrix[i][i];
                    for(int j=1;j<=n+1;j++)
                    {
                        Matrix[i][j]=Matrix[i][j]/pivot;
                    }
            }

        return Matrix;
    }
*/
}
public class Main
{
    public static List<Double> listX = new ArrayList();
    public static List<Double> listY = new ArrayList();
    public static void inputData2D(int totalDataSize)
    {
       Scanner scanner = new Scanner(System.in);
       for(int i=0;i<totalDataSize;i++)
       {
           System.out.print("Enter x"+(i+1)+" : ");
           double x = scanner.nextDouble();
           listX.add(x);
           System.out.print("Enter y"+(i+1)+" : ");
           double y = scanner.nextDouble();
           listY.add(y);
       }

    }
    public static void main(String[] args)
    {
       Functions functions = new Functions();
       Scanner scanner = new Scanner(System.in);
       System.out.print("How many (x,y) inputs : ");
       int totalData = scanner.nextInt();
       inputData2D(totalData);
       double[][] matrix = functions.makeMatrix(listX,listY,totalData);
       List<Double> listA = functions.solutionGJM(matrix,3);
       System.out.println("The straight line is : y="+listA.get(0)+"+"+listA.get(1)+"x"+"+"+listA.get(2)+"x2");
    }
}