---

uses graphabc;
function f(x: real): real;
  begin f := sin(x) end;
var x, y: integer;
begin
  line(0, 240, 640, 240);
  line(320, 0, 320, 480);
  line(640, 240, 635, 235);
  line(640, 240, 635, 245);
  textout(635, 250, 'x');
  for x := 1 to 15 do
    line(x * 40, 238, x * 40, 242);
  { ... }
  for x := 1 to 640 do
    lineto(x, trunc(-40 * f((x - 320) / 40) + 240));
end.