/*
   this program wants to calculate the sum of the square roots
   of i*i - 10*i + 23 for all values of i over a certain range.

   It wants to avoid trying to calculate the square root of a 
   negative, not only printing an error message if one is encountered,
   but also returning -1 as the whole value of the sum, as a
   second signal that something isn't right.

   This version does not succeed at all of its goals.
*/


#include "library.h"

double f(const double i)
{ const double s = i*i - 10*i + 23;
  if (s < 0)
  { print("Error - square root of negative: ");
    print(s);
    print(" when i = ");
    print(i);
    new_line();
    return -1; }
  return sqrt(s); }

double sum(const int from, const int to)
{ if (from <= to)
    return f(from) + sum(from + 1, to);
  else
    return 0; }

void main()
{ print(sum(0, 10));
  new_line(); }