Untitled

//REGULA FALSI
#include<stdio.h>
#include<math.h>
float f(float x){
    return(x*x*x-4*x-9);
}
int main(){
    float a,b,x,aerr;
    int itr=0,flag=0;
    do{
        printf("\nEnter the two values for interval: ");
        scanf("%f%f",&a,&b);
        if(f(a)*f(b)<0){
            printf("\n The root of the equation lies between %.2f and %.2f",a,b);
            flag=1;
        }
        else
        printf("\n Wrong Intervals!!!");
    }while(flag==0);
    printf("\n Enter the allowed error");
    scanf("%f",&aerr);
    do{
        itr++;
        x=(a*f(b)-b*f(a))/(f(b)-f(a));
        printf("\n%d Iteration, value of X[%d] is=%f,value of f(x)=%f",itr,itr,x,f(x));
        if(fabs(f(x))<=aerr){
        printf("\n the root of the equation is %f after %d iteration",x,itr);
        flag=0;
    }
    else if(f(a)*f(x)<0)
    b=x;
    else
    a=x;
}while (flag==1);
return 0;
}