secant method

#include<stdio.h>
#include<conio.h>
#include<math.h>
float fun(float a)
{
float b;
b=a*a-4*a-10;    /*just change the equation according to your wish */
return(b);
}
float main()
{
float x1,x2,x3,f1,f2,f3,e;
printf("enter the values of x1 and x2");
scanf("%f",&x1);
scanf("%f",&x2);
printf("x1\t      x2\t         x3\t          f1\t            f2\t");
do
{
f1=fun(x1);
f2=fun(x2);
x3=((x1*f2)-(x2*f1))/(f2-f1);
e=fabs((x3-x2)/(x3));
x1=x2;
x2=x3;

printf("\n%f\t    %f\t     %f\t     %f\t    %f\t",x1,x2,x3,f1,f2);

}
while(e>0.001);

getch();
}