#include 
#include 

// 传递函数指针f时，tabulate函数显示函数f的值
void tabulate(double (*f)(double), double first, double last, double incr);

int main(void)
{
 double initial, final, increment;

 printf("Enter initial value: ");
 scanf("%lf", &initial);

 printf("Enter final value: ");
 scanf("%lf", &final);

 printf("Enter increment: ");
 scanf("%lf", &increment);

 printf("\n x cos(x)"
  "\n ------- -------\n");
 tabulate(cos, initial, final, increment);

 printf("\n x sin(x)"
  "\n ------- -------\n");
 tabulate(sin, initial, final, increment);

 printf("\n x tan(x)"
  "\n ------- -------\n");
 tabulate(tan, initial, final, increment);

 return 0;
}

void tabulate(double (*f)(double), double first, double last, double incr)
{
 double x;
 int i, num_intervals;

 num_intervals = ceil((last - first) / incr);
 for (i = 0; i <= num_intervals; i++) {
 x = first + i * incr;
 printf("%10.5f %10.5f\n", x, (*f)(x));
 }
}