program grafic;
Uses Crt,Graph;
Type Func=Function(x:Real):Real;
     Corners=array[1..4] of Integer;
     Gabarits=array[1..4] of Real;
Var
    Corn:Corners;
    Gab:Gabarits;
    d,r,ge:Integer;
    c:Char;
    a,b:real;
    n:Word;


Procedure Window(Corn:Corners;col:Word);
  begin
  SetColor(col);
  Rectangle(Corn[1],Corn[2],Corn[3],Corn[4]);
  SetViewPort(Corn[1],Corn[2],Corn[3],Corn[4],ClipOn);
end{Window};

Procedure DrawGraph(Corn:Corners;var Gab:Gabarits;F:Func;a,b:Real;n:Word;col:Word);
  var x,y,h,miny,maxy,kx,ky:Real;
     i:Integer;
 function XPixel(x:Real):Word;
  begin XPixel:={Corn[1]+}Round(kx*(x-Gab[1])); end;
 function YPixel(y:Real):Word;
  begin YPixel:=Corn[4]-Corn[2]-Round(ky*(y-Gab[2])); end;
 procedure Axes(col:Word);
  var xp,yp,c:Word;
  begin
   c:=GetColor; SetColor(col);
   if (0>Gab[1])and(0<Gab[3]) then
    begin xp:=XPixel(0);
          Line(xp,0,xp,Corn[4]-Corn[2]); {по вертикали}
   end;
   if (0>Gab[2])and(0<Gab[4]) then
    begin yp:=YPixel(0);
          Line(0,yp,Corn[3]-Corn[1],yp); {по горизонтали}
   end;
   Setcolor(c);
 end{Axes};
 begin {DrawGraph}
   h:=(b-a)/n; {Шаг построения графика}
  if (Gab[3]<=Gab[1]) or (Gab[4]<=Gab[2]) then begin {автогабариты}
   Gab[1]:=a; Gab[3]:=b;
   maxy:=-1E38;miny:=+1E38;
   x:=a;
   for i:=0 to n do begin
    y:=F(x);
    if y>maxy then maxy:=y;
    if y<miny then miny:=y;
    x:=x+h;
   end;
   Gab[2]:=miny; Gab[4]:=maxy;
  end;
  kx:=(Corn[3]-Corn[1]-1)/(Gab[3]-Gab[1]);
  ky:=(Corn[4]-Corn[2]-1)/(Gab[4]-Gab[2]);
  Axes(green);
  x:=a;
  for i:=0 to n do begin
    y:=F(x);
    PutPixel(XPixel(x),YPixel(y),col);
    x:=x+h;
   end;
end{DrawGraph};


function F1(x:Real):Real; Far;
 begin F1:=sin(x/3)
  end;

begin {main}
 d:=Detect; InitGraph(d,r,'d:bp'); ge:=Graphresult;
 if ge<> grOK then Writeln(GraphErrorMsg(ge))
 else begin
{  Corn[1]:=GetMaxX div 4; Corn[2]:=GetMaxY div 4;
  Corn[3]:=3*GetMaxX div 4; Corn[4]:=3*GetMaxY div 4 ;{посередине}
  Corn[1]:=50; Corn[2]:=150;
  Corn[3]:=600; Corn[4]:=400;
  Window(Corn,Green);
  Gab[1]:=-10; Gab[2]:=-10; Gab[3]:=20; Gab[4]:=-10;
  a:=-10; b:=18{2*Pi};
  DrawGraph(Corn,Gab,F1,a,b,10000,9);
  c:=readkey;
 end;
end.