title: How to call a void function in C
body: <p>Ok so I have written this code with four different functions, and the main purpose of it is to display in a table from angles 0-90 what the angle, time, distance of a velocity is. the velocity is inputed from the user.
  But when I call the void function that is making the function I get an error "undefined reference to `create_table'" Here is my code.</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;stdlib.h&gt;
  #include &lt;math.h&gt;
  
  #define G 9.8   /* gravitation acceleration 9.8 m/s^2 */
  #define PI 3.141592654
  
  void create_table(double v);
  double Projectile_travel_time(double a, double v);
  double Projectile_travel_distance(double a, double v);
  double degree_to_radian(double d);
  
  int main(void)
  {
      int n;
      double velocity;
  
      printf ("please enter the velocity at which the projectile is launched (m/sec): ");
      n = scanf("%lf" ,&amp;velocity);
  
      if(n != 1)
      {
          printf("Invlid input. Bye...");
          exit(1);
      }
  
      while (velocity &lt; 0 )
      {
          printf ("please enter a positive number for velocity: ");
          n = scanf("%lf", &amp;velocity);
          if(n != 1)
          {
              printf("Invlid input. Bye...");
              exit(1);
          }
      }
      create_table(velocity);
  
  
      return 0;
  }
    void create_table(double v)
      {
          printf("Angle      t      d\n");
          printf("(deg)    (sec)   (m)\n");
  
          double a,i;
          for( a=0; a&lt;=90; a+=5)
          {
              for(i=0; i&lt;=2; i++)
              {
                  double t = Projectile_travel_time(a, v);
                  double s = Projectile_travel_distance(a, v);
                  printf("%d       %d       %d\n", a, t, s);
  
              }
          }
  
  
      }
      double Projectile_travel_time(double a, double v)
      {
          double t = ((2*v*sin(degree_to_radian(a)))/(G));
          return t;
      }
      double Projectile_travel_distance(double a, double v)
      {
          double d = ((v*v)/G)*sin(2*degree_to_radian(a));
          return d;
      }
  
      double degree_to_radian(double d)
      {
           double r = d*atan(1) * 4 / 180;
           return r;
      }
  </code></pre>
  
  <p>any help would be appreciated. 
  thanks</p>
  
  <p><em>edit</em> I have edited the code but now have encountered another problem with my outputs being completely off. Any suggestions how my functions are incorrect? </p>