Program Mencari Akar-akar Persamaan Suku Banyak (Metode Secant)

1. Persamaan yang dicari : 9x^4 + 2x^3 + 3x - 1 = 0
nilai awal x1 : 5
nilai awal x2 : 6
nilai error      : 0.00001
total iterasi    : 15

2. Kode program (bahasa C) :
/*mencari akar persamaan dari persamaan 9x^4 + 2x^3 + 3x - 1 = 0*/

#include<stdio.h>
#include<math.h>

double power(double, int);
double value(double);
double calculate(double, double);

main()
{
    double x1, x2, e;
    int itr;
    printf ("Input Nilai Awal x1 : ");
    scanf ("%lf", &x1);
    printf ("Input Nilai Awal x2 : ");
    scanf ("%lf", &x2);
    printf ("Input Nilai Error : ");
    scanf ("%lf", &e);
    printf ("Input Total Iterasi : ");
    scanf ("%i", &itr);

    int i=1;
    double xt, error=1.0000;

     printf("\n");
    printf ("+------------+--------+--------+--------+-----------+\n");
    printf ("|Iterasi ke- |   xl   |   xb   |   xt   |  |error|  |\n");
    printf ("+------------+--------+--------+--------+-----------+\n");

    for (i=1;(i<itr) && (error>e);i++)
    {
        xt = calculate(x1, x2);
        printf ("|     %3i    |%8.4lf|%8.4lf|%8.4lf|%11.6lf|\n", i, x1, x2, xt, cabs(value(xt)));
        error = cabs(value(xt));

        x1=x2;
        x2=xt;

    }
    printf ("+------------+--------+--------+--------+-----------+\n");
}

double power(double number, int power)
{
    double result = 1.00;

    if (power == 0.0)
    {
        return result;
    }

    int i;

    for (i = 1; i <= power; i++)
    {
        result *=number;
    }

    return result;
}

double value(double x)
{
    return ((4*(power(x,3))) - (15*(power(x,2))) + 17*x - 6);
}

double calculate(double xl, double xb)
{
    return (xb - ((xb-xl)/(value(xb)-value(xl)))*value(xb));
}

3. Hasil keluaran :

4. Hasil akhir :

x = 2

berhenti pada iterasi ke-11, di mana nilai error sudah 0

Nama : Adhia Saputra

NIM   : D1042131046

Teknik Informatika UNTAN 2013 (Reguler B)