BISECTION METHOD IN C

Bisection in C

#include<stdio.h>
#include <math.h>
#define ESP 0.01
//#define F(x) (x)*(x)*(x) + (x)*(x) + (x) + 7
#define F(x) (x)*(x) - 3
//#define F(x) (x)*(x)*(x)-0.165*(x)*(x)+0.0003993
void main()
{
  int i = 1;
  float low,up,mid;
  double flower,fupper,fmiddle;

  float error;
  printf("\nEnter the lower value: ");
  scanf("%f",&low);

  printf("\nEnter the upper value: ");
  scanf("%f",&up);
	
  printf("\n___________________________________________________________________________________________\n");
  printf("\niter     low\t           mid\t          up\t     f(lower)\t        f(mid)\t       f(upper)");
  printf("\n___________________________________________________________________________________________\n");
	
  do
  {
	mid=(low+up)/2;
	flower=F(low);
	fupper=F(up);
	fmiddle=F(mid);

	printf("\n%d \t%f \t%f \t%f \t%lf \t%lf \t%lf", i, low,mid,up,flower,fmiddle,fupper);
  if(flower*fmiddle<0)
   {
	up=mid;
   }

   else
   {
	low=mid;
   }
	i++;
	error=up-low;
	printf("\tERROR %d =%f",i,fabs(error));	
  }while(fabs(up-low)>ESP);
printf("\n______________________________________________________________________________________________\n");

printf("\n\nApp.root = %f\n\n",mid);

}