//for implementation of regula Secants Method for 
// solving equations 
#include<stdio.h> 
#include<math.h>
#define MAX_ITER 1000000   
#define err 0.00001

double f(double x) 
{  
return x*x*x - x - 1; 
} 
// Prints root of f(x) in interval [a, b] 

void regulaFalsi(double a, double b) 
{ 
int count=0;
    if (f(a) * f(b) >= 0) 
    { 
        printf("You have not assumed right a and b\n"); 
        return; 
    } 
    printf("finding the approx root of eqn. by Secant method\n");
    double c = a;  // Initialize result
    printf("\na\t\tb\t\tf(a)\t\tf(b)\t\tc\t\tf(c)\n"); 
    
    for (int i=0; i < MAX_ITER; i++) 
    {
        printf("%.4f \t\t%.4f \t\t%.4f\t\t%.4f",a,b,f(a),f(b));
        // Find the point that touches x axis 
        c = (a*f(b) - b*f(a))/ (f(b) - f(a));
        printf("\t\t%.4f\t\t%.4f\n",c,f(c));
        // Check if the above found point is root 
       if (f(c)<=0.00001 && f(c)>=-0.00001) 
       {    // if(fabs(a-c)>err)
        break; 
        } 
        // Decide the side to repeat the steps 
           a=b;
           b=c;
                       
            ++count;
    } 
    printf( "The value of root is :%.4f ", c); 
    printf(" the no of iterations required is %d",(count+1));
} 

void GetRootRange(double *L, double *U)
 {
 double y;
 for(y=-999999.0l;y<999999.0l;y=y+0.1)
 {
 if(f(y)*f(y+0.1)<0.0)
 {fflush(stdin);
 *L=y;*U=y+0.1;
 return;
 }
 }
 }
// Driver program to test above ftion :""

int main() 
{ 
    // Initial values assumed 
    double a , b  ;
    GetRootRange(&a,&b);
    regulaFalsi(a, b); 
    return 0; 
}