#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}

int Factorial(int n)
{
 int result = n;
 for (int i = 1; i < n; i++)
 {
  result *= i;
 }
 return result;
}

double Lagrange(const double *x, const double *y, const double x0)
{
 double result = 0;
 for(int i=0;i<10;i++)
 {
  double denum = 1, num = 1, temp=0;
  for(int j=0;j<10;j++)
  {
   if(i!=j)
   {
    num *= x0 - x[j];
    denum *= x[i] - x[j];
   }
  }
  result += num / denum * y[i];
 }
 return result;
}
//--------------------------------------------------------------------------------
double Newton(const double *x, const double *y, const double x0)
{
 double h = x[1] - x[0];
 double result = y[0];
 double dDeltaYArray[10][10] = { 0 };
 for (int i = 0; i < 10; i++)
 {
  dDeltaYArray[i][0] = y[i];
 }

 for (int i = 1; i < 10; i++)
 {
  for (int j = 0; j < 10 - i; j++)
  {
   dDeltaYArray[j][i] = dDeltaYArray[j + 1][i - 1] - dDeltaYArray[j][i - 1];
  }
 }

 for (int i = 1; i < 10; i++)
 {
  double num = dDeltaYArray[0][i], denum = Factorial(i), term = 0;
  for (int j = 0; j < i; j++)
  {
   num *= x0 - x[j];
   denum *= h;
  }
  term = num / denum;
  result += term;
 }
 return result;
}
//--------------------------------------------------------------------------------

void MainWindow::on_pushButton_clicked()   // lagrange
{
    const double *arrayX = new double[10]{0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55,0.60};
    const double *arrayY = new double[10] {0.86, 0.819, 0.779, 0.741, 0.705, 0.670, 0.638, 0.606, 0.577, 0.549};
    const double x1 = 0.3119, x2=0.5031;

   double result = Lagrange(arrayX,arrayY,x1);
    ui->textBrowser->append("Lagrange Polynom \n Interpolation = " + QString::number(result));
}

void MainWindow::on_pushButton_2_clicked() //newtons
{
    const double *arrayX = new double[10]{0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55,0.60};
    const double *arrayY = new double[10] {0.86, 0.819, 0.779, 0.741, 0.705, 0.670, 0.638, 0.606, 0.577, 0.549};
 const double x1 = 0.3119, x2=0.5031;
 double result = Newton(arrayX,arrayY,x2);

 ui->textBrowser->append("Newton Polynom \n Interpolation = " + QString::number(result));

}