Question

Direct Search Method

– Write a C code to find all the roots of equation between 1 and 10 by using direct search method with

Deltax= 0. 01: 49.55x− 12.8x^2+x^3=59.5

Answer 1

A simple method could be created to achieve the same functionality in code.

#include <stdio.h>
#include <math.h>
#define PI 3.14159265

double f(double x);
double direct(double a, double b, int n);

int main()
{
       double x0 = 1, xn = 10;
       // Considering number of steps 1000
       int n = 1000;

       printf( "The root is %f\n", direct(x0, xn, n) );

       return 0;
}

double f(double x)
{
       double y;
       y = 49.55*x - 12.8*x*x + x*x*x - 59.5;
       return y;
}

// Method to search root via direct method
double direct(double a, double b, int n)
{
       int i;
       double dx, x, f1, f2;
       dx = 0.01;
       f1 = f(a);
       for (i = 1; i <= n; i++) {
           x = a + dx * i;
           f2 = f(x);
           if (f1 * f2 <= 0) break;
           f1 = f2;
       }
       return x - dx/2;
}

Happy Coding!