Program to find the roots of a polynomial equation using method of false position

#include<stdio.h>

#include<conio.h>

#include<math.h>

#define f(x) x*x*x-4*x+1

int main()

{

float x0,x1,e,y0,y1,x2,y2;

int i,n;

//clrscr();

printf("enter the initial guesses\n");

scanf("%f%f",&x0,&x1);

printf("enter the prescribed precision value\n");

scanf("%f",&e);

printf("enter the maximum number of iteration\n");

scanf("%d",&n);

y0=f(x0);

y1=f(x1);

if(y0*y1 > 0)

{

  printf("initial guesses are not suitable\n");

  return (0);

  //exit(0);

}

//printline();

printf("iter\tX0\tF(X0)\tX1\tF(X1)\tX2\tF(X2)\n");

//printline();

//for(i=1;i<=n;i++)

{

  x2=(x0*y1-x1*y0)/(y1-y0);

  y2=f(x2);

  printf("  %d\t%.2f\t%.2f\t%.2f\t%.2f\t%.2f\t%.2f\n",i,x0,y0,x1,y1,x2,y2);

  if ((fabs(y2))<=e)

  {

    //printline();

    printf("converges to the root\n");

    printf("number of iteration is %d\n",i);

    printf("root is %.2f\n",x2);

    getch();

    return (0);

    //exit(0);

  }

  if (y0*y2>0)

  {

    x0=x2;

    y0=y2;

  }

  else

  {

    x1=x2;

    y1=y2;

  }

}

//printline();

printf("does not converges to the root in %d iteration",n);

getch();

}