浮点数的比较,浮点数存在误差

#include<stdio.h>
#include<math.h>
#include<float.h>
void Fun(double a,double b,double c)
#define EPS 0.00001
{
 double x1;
    double x2;
 double d=b*b-4*a*c;
 if(-EPS<=a &&a <=EPS)//a==0
 {
  x1=x2=-c/b;
  printf("x1=%f,x2=%f\n",x1,x2);
 }
 else
 {
   if(d>EPS)//d>0
  {
   x1=(-b+sqrt(d))/2*a;
   x2=(-b-sqrt(d))/2*a;
   printf("x1=%f,x2=%f\n",x1,x2);
  }
  else
  {
   if(-EPS<=d&&d<=EPS)//d<0
   {
    x1=x2=-b/2*a;
    printf("x1=%f,x2=%f\n",x1,x2);
   }
   else//d<0
   {
    printf("无实根\n");
   }
  }
 }
}
int main()
{
 Fun(0,1,2);
 Fun(1,4,1);
 return 0;
}