Secant Method Program

secant.c

#include<stdio.h>
#include<math.h>
#define e 0.001
#define F(x) (2*x)-3
float frac(float a)
{
       float f1;
       f1=a*a-3*a+2;
       return f1;
}
int main()
{
       float x1,x2,f1=0,f2,er,d;
       printf("F(x) = x^2-3x+2\n\n");
       printf("Enter the value of x1: ");
       scanf("%f",&x1);
       printf("\nx1 = %f",x1);
       printf("\n________________________________________________________________________________\n");
        
       printf("     x1      |       x2      |      f1       |       f'1      |  |(x2-x1)/x2|  |  \n");
       printf("--------------------------------------------------------------------------------\n");
       do
       {
              f1=frac(x1);
              d=F(x1);
              x2=x1-(f1/d);
              er=fabs((x2-x1)/x2);
           printf("  %f   |    %f   |     %f  |     %f  |      %f  |   \n",x1,x2,f1,d,er);
              x1=x2;
       }
       while(er>e);
       printf("--------------------------------------------------------------------------------\n\n");
       printf("\n  Root of the equation is: %f\n",x2);

}