доработать

#include <stdio.h>
#include <math.h>
#include <iostream>
typedef double (*Pfun)(const double, const double );
double cosh (const double x , const double eps);
double a; int n,d;
void printtabl (Pfun, const double Xn, const double Xk, const double dX,  const double eps);
int main(){
    double Xn, Xk, dX, eps;
    printf ("Enter Xn, Xk, dX, eps \n");
    scanf ("%lf%lf%lf%lf" , &Xn, &Xk, &dX, &eps);
    printtabl(cosh, Xn, Xk, dX, eps);
    return 0;
}
 
void printtabl (Pfun fun, const double Xn, const double Xk, const double dX, const double eps){
    printf ("--------------------------------------------------------------\n");
printf ("|     X   |     Y     |      n     |\n");
printf ("------------------------------------------------------------------\n");
double x;
for (double x = Xn; x<=Xk; x+=dX)
    {a=atan(x);
    printf("|%9.2lf   |%14.6g    |%14.6g    |%9.1d      |\n", x , fun(x, eps),a, n);
    printf ("--------------------------------------------------------------\n");}
}
double cosh (const double x, const double eps  ) {
    const int MaxIter = 500;
    double ch=0.0001, y=ch, z;
    z=0-1; d=0; 
    for ( n=0; fabs(ch)>eps; n++)   {
    ch=((pow(z,(n+1))/(pow(x,(2*n+1))*(2*n+1))));
    y+=ch;
        if (n>MaxIter) return 0;
        }
a=atan(x);
y=y+(3.1415926535898/2);
return y;
}