(*  VERSION 0002  *)
module plot6;


(*..................................................................*)
(*                           PLOTLIB                                *)
(*  Plotlib is a collection of plot routines to aid in graphics     *)
(*  programs. The routines were originally published in BYTE as     *)
(*  'Drawing with UCSD Pascal and the Hiplot Plotter' by Dr. James   *)
(*  Stork, Oct 1981. The routines have been modified to run with    *)
(*  a MicroAngelo graphics terminal by Ray Hopkins, 8 Chestnut Hill *)
(*  Ct., Cinnaminson N.J. (609) 829-4686.                           *)
(*..................................................................*)

type
{$I PLOTLIB.TYP}

const
{$I PLOTLIB.CON}
      
var
    xpos,ypos :external real;

(*$IPLOTLIB.DEF*)
{$ISTDLIB.DEF}

external procedure plotsymbol(sym:integer;height:real);

procedure plotarray(nopoints,freq,sym:integer;
    px,py,xmin,xmax,ymin,ymax,height,xlen,ylen:real;
    x,y: coord);
    
var pen,i:integer;

begin
  if nopoints>250 then
    begin
      outp($88);
      write('too many points');
      readln;
      outp($88);
      exit;
    end;
  if (py+ylen>7) or (px+xlen>10) then
    begin
      outp($88);
      write('data is off screen. Type ret');
      readln;
      outp($88);
      exit;
    end;
  xlen:=(xmax-xmin)/xlen;
  ylen:=(ymax-ymin)/ylen;
  if freq<0 then pen:=1
  else pen:=2;
  freq:=abs(freq);
  plotline(1,((x[1]-xmin)/xlen)+px,((y[1]-ymin)/ylen)+py);
  for i:=2 to nopoints do
    begin
      plotline(pen,((x[i]-xmin)/xlen)+px,((y[i]-ymin)/ylen)+py);
      if freq>0 then
        if ((i+1)mod freq=0) then plotsymbol(sym,height);
    end;
  end; {plotarray}
  
modend.