createCanvas(400, 400);

}

​

function draw() {

  background(200);

​

  var period = 1000.0; // milliseconds

  var angle = TWO_PI * millis()/period;

  var centerX = width/2;

  var centerY = height/2;

  var amplitudeX = 100; 

  var amplitudeY = 100; 

  var frequency = 1.0;

  var phaseX = 0; 

  var phaseY = 0; 

  var px = centerX + amplitudeX * sin(phaseX + frequency * angle);

  var py = centerY + amplitudeY * cos(phaseY + frequency * angle); 

  ellipse(px, py, 40, 40);

}