SECANT METHOD

Finding The Roots Of The Given Equation By Using Secant Method

Source code :-

// Solve by Secant method [ 2x-log10(x)-7=0 ]

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
float f(float x)
{
    return (2 * x - log10(x) - 7.0); // Replace With given Equation
}
int main()
{
    float a, b, x, y, h, err;
    int n = 0, d;
    printf("Enter the lower limit: ");
    scanf("%f", &a);
    printf("\nEnter the upper limit: ");
    scanf("%f", &b);
    if (f(a) * f(b) > 0)
    {
        printf("\nRoot does not exists between %f and %f\n", a, b);
        exit(0);
    }
    printf("\nEnter the correction upto decimal place: ");
    scanf("%d", &d);
    err = (5.0 / pow(10, d));
    x = 0;
    printf("\n\n  N\tXn(+ve) \t  Hn\t\tXn+1(A+Hn)\n");
    printf("\n--------------------------------------------------\n");
    do
    {
        y = x;
        h = -(f(a) / (f(b) - f(a))) * (b - a);
        x = a + h;
        printf("\n %2d \t%2.5f \t%+2.5f \t %+2.5f\n", ++n, y, h, x);
        b = x;
    } while (fabs(x - y) >= err);
    printf("\n\n\t  The root is: x=%f\n\n\n", x);
    return 1;
}

Input-Output :-

abhi@hp-15q-laptop:~$ gcc secant.c
abhi@hp-15q-laptop:~$ ./a.out

Enter the lower limit: 2

Enter the upper limit: 5

Enter the correction upto decimal place: 5


  N     Xn(+ve)           Hn            Xn+1(A+Hn)        

--------------------------------------------------

  1     0.00000         +1.76776         +3.76776

  2     3.76776         +1.78975         +3.78975

  3     3.78975         +1.78927         +3.78927

  4     3.78927         +1.78928         +3.78928


          The root is: x=3.789279