extern double arc_length_from_t ( double y_eye , double z_eye , double row , double col , double t ) ;
extern void audit ( const char * ) ;
extern void begin_wait_message ( char *msg , int ok_to_abort ) ;
extern double compute_checker ( double row , double col ) ;
extern double compute_spiral ( double row , double col ) ;
extern int compute_threaded ( unsigned char *image ) ;
extern double curve ( double radius ) ;
extern void delete_arc_table () ;
extern void end_wait_message () ;
extern void end_printing ( HWND hwnd ) ;
extern void error_message ( char *msg ) ;
extern double find_t ( double y_eye , double z_eye , double row , double col ) ;
extern int initialize_for_printing ( HWND hwnd ) ;
extern void insufficient_memory ( char *msg ) ;
extern int make_arc_table ( int table_length ) ;
extern int save_img_file ( HWND hwnd , char *name ) ;
extern void save_img_file_init () ;
extern void setpos_wait_message ( double pos ) ;
extern int user_pressed_escape () ;

extern "C" {
LRESULT CALLBACK FrameWndProc ( HWND , UINT , WPARAM , LPARAM ) ;
LRESULT CALLBACK ImageWndProc ( HWND , UINT , WPARAM , LPARAM ) ;
INT_PTR CALLBACK DialogAbout ( HWND hdwnd , UINT message ,
                            WPARAM wParam , LPARAM lParam ) ;
INT_PTR CALLBACK DialogVortexParams ( HWND hdwnd , UINT message ,
                                      WPARAM wParam , LPARAM lParam ) ;
INT_PTR CALLBACK DialogPrintParams ( HWND hdwnd , UINT message ,
                                  WPARAM wParam , LPARAM lParam ) ;
}
