var ctx = document.getElementById('tutorial').getContext('2d');

  ctx.fillRect(0,0,300,300);

  for (var i=0;i<3;i++) {

    for (var j=0;j<3;j++) {

      ctx.save();

      ctx.strokeStyle = "#9CFF00";

      ctx.translate(50+j*100,50+i*100);

      drawSpirograph(ctx,20*(j+2)/(j+1),-8*(i+3)/(i+1),10);

      ctx.restore();

    }

  }

function drawSpirograph(ctx,R,r,O){

  var x1 = R-O;

  var y1 = 0;

  var i  = 1;

  ctx.beginPath();

  ctx.moveTo(x1,y1);

  do {

    if (i>20000) break;

    var x2 = (R+r)*Math.cos(i*Math.PI/72) - (r+O)*Math.cos(((R+r)/r)*(i*Math.PI/72))

    var y2 = (R+r)*Math.sin(i*Math.PI/72) - (r+O)*Math.sin(((R+r)/r)*(i*Math.PI/72))

    ctx.lineTo(x2,y2);

    x1 = x2;

    y1 = y2;

    i++;

  } while (x2 != R-O && y2 != 0 );

  ctx.stroke();

}