Newton Raphson Method Using Pointers – C code

I’m trying to figure out where i’m missing . it’s a Newton Raphson Method Using Pointers.But not returning any answer…

#include <stdio.h>
#include <math.h>

double newton(double (*f)(), double (*df)(), double y, double tol)
{
double x=y/2;
while(fabs(f(x,y)/df(x))>tol)
{
x=x-f(x,y)/df(x);
}
return x;
}

int main()
{
double y,x;
scanf(“%lf”,&y);
x=newton(f,df,y,1e-5);
printf(“%.2lf”,x);
return 0;
}

may you help me?