koreg.cpp

/*    Program ini gunanya untuk:

      1.  itung koefisien korelasi.
      2.  cari persamaan regresi.
                    */

#include <iostream>
using namespace std;
#include <stdio.h>
#include <math.h>
#include <stdlib.h>

float set1[100], set2[100];

void corr_coeff(float[], float[], int);
void regression(float[], float[], int);

int main()
{

    int n, i, x;
    char ans;

    cout << "\n Mau berapa data yang ingin diinput:   ";
    cin >> n;

    cout << "\n\n Masukkan nilai untuk set data yang pertama: \n";

    for (i = 0; i <= n - 1; i++)
        cin >> set1[i];
    cout << "\n\n Masukkan set data yang kedua: \n";

    for (i = 0; i <= n - 1; i++)
        cin >> set2[i];

    do
    {

        cout << " 1.    hitung koefisien korelasi  \n";
        cout << " 2.    cari persamaan regresi \n";
        cout << " 3.    keluar dari program \n";

        cout << "\n\n\n Ayo, mo pilih yang mana:? ";
        cin >> x;

        switch (x)
        {

        case 1:
            cout << "\n Koefisien korelasinya adalah:  ";
            corr_coeff(set1, set2, n);

            break;

        case 2:
            cout << "Persamaan regresinya adalah: \n";
            regression(set1, set2, n);

            break;

        case 3:

            cout << "\n Makasih";
            cout << "\n\n\n\n\n tekan tombol keyboard apa saja untuk keluar.";

            cin.get();

            exit(0);

        default:
            cout << "\n\n Pilihannya salah. Coba lagi deh";

            cin.get();
        }

        cout << "\n\n Lanjut gak?  (y/n)";
        cin >> ans;

    } while (ans == 'y' || ans == 'Y');

    cout << "\n Makasih";
    cout << "\n\n\n\n\n tekan tombol keyboard apa saja untuk keluar.";

    cin.get();
}

void corr_coeff(float x[], float y[], int p)
{
    int i;
    float sx = 0.0, sy = 0.0, sxy = 0.0, sxs = 0.0, sys = 0.0;
    float mx = 0.0, stddivx = 0.0, my = 0.0, stddivy = 0.0;
    float num, den, rxy;

    for (i = 0; i <= p - 1; i++)
    {
        sx = sx + x[i];
        sy = sy + y[i];
        sxy = sxy + (x[i] * y[i]);
        sxs = sxs + (x[i] * x[i]);
        sys = sys + (y[i] * y[i]);
    }

    mx = sx / p;
    my = sy / p;
    stddivx = sqrt(((sxs / p) - (mx * mx)));
    stddivy = sqrt(((sys / p) - (my * my)));

    num = (sxy / p) - (mx * my);
    den = stddivx * stddivy;
    rxy = num / den;

    cout << rxy;
}

void regression(float x[], float y[], int p)
{
    int i;
    float sx = 0.0, sy = 0.0, sxy = 0.0, sxs = 0.0, sys = 0.0;
    float mx = 0.0, stddivx = 0.0, my = 0.0, stddivy = 0.0;
    float num, den, rxy, r;

    for (i = 0; i <= p - 1; i++)

    {
        sx = sx + x[i];
        sy = sy + y[i];
        sxy = sxy + (x[i] * y[i]);
        sxs = sxs + (x[i] * x[i]);
        sys = sys + (y[i] * y[i]);
    }

    mx = sx / p;
    my = sy / p;
    stddivx = sqrt(((sxs / p) - (mx * mx)));
    stddivy = sqrt(((sys / p) - (my * my)));

    num = (sxy / p) - (mx * my);
    den = stddivx * stddivy;
    rxy = num / den;

    r = rxy * (stddivy / stddivx);

    cout << "\n\n\n Y =" << my << "+" << r << "*"
         << "(X - " << mx << ")";
}