(*
 * plotlib - graphics graph plotting package
 *
 *)

const
   green     = 1;
   red       = 1;
   yellow    = 1;
   mark_x    = 4;        {size of marker}
   mark_y    = 2;
   numtics   = 5;        {number of ticks in scales}
   maxstyle  = 4;

var
   maxx:    real;      {logical dimensions of screen}
   minx:    real;
   maxy:    real;
   miny:    real;
   xstep:   real;
   ystep:   real;
   nxsteps: integer;
   nysteps: integer;
   color:   integer;

var
   phys_maxx: integer;    {physical dimensions of graphics area}
   phys_minx: integer;
   phys_maxy: integer;
   phys_miny: integer;

var
   Graph_Driver:  integer;
   Graph_Mode:    integer;
   Text_Mode:     word;

const
   Driver_Path = '';


function get_phys_x(vx: real): integer;
function get_phys_y(vy: real): integer;
procedure connect(x1,y1,x2,y2: real);
procedure tick(x1,y1: real);

procedure determinescale (var world_min:     real;
                          var world_max:     real;
                          var stepsz:        real;
                          var stepcnt:       integer;
                              maxstep:       integer);

procedure marker(x,y: real; style: integer);

procedure labely(y: real);
procedure ticky(y: real);

procedure labelx(x: real);
procedure tickx(x: real);

procedure putxscale;
procedure putyscale;

procedure border;

procedure plot_data(variable_number: integer;
                    x:               integer;
                    y:               real);

procedure event(x: integer; note: string);

procedure open_graph;
procedure close_graph;