sine cosine Gradient

[SWF(width=600,height=500,frameRate=30)]
var canvas:BitmapData=new BitmapData(600,500,false,0x000000);
addChild(new Bitmap(canvas));
var size:Number=canvas.width*canvas.height;
var w:Number=canvas.width;
var wd:Number=1/w;
var pix:Vector.<uint> = new Vector.<uint>();
var sin:Number;
var cos:Number;
var dx:Number=110;
var dy:Number=52;
addEventListener(Event.ENTER_FRAME, onLoop);
function onLoop(evt:Event):void {
	dx+=0.001;
	canvas.lock();
	for (var i:int = 0; i<size; i++) {
		var xp:Number=i%w;
		var yp:Number=int(i*wd);
		var xx:Number=xp*0.05+dx;
		var yy:Number=yp*0.05+dy;
		var t:Number= (xx * yy) % 3.14159265;
		//compute sine
		// technique from http://lab.polygonal.de/2007/07/18/fast-and-accurate-sinecosine-approximation/
		// by Michael Baczynski
		if (t<0) {
			sin=1.27323954*t+.405284735*t*t;
		} else {
			sin=1.27323954*t-0.405284735*t*t;
		}
		//compute cosine: sin(t + PI/2) = cos(t)
		t+=1.57079632;
		if (t>3.14159265) {
			t-=6.28318531;
		}
		if (t<0) {
			cos=1.27323954*t+0.405284735*t*t;
		} else {
			cos=1.27323954*t-0.405284735*t*t;
		}
		var c:Number=sin+cos*cos*cos;
		// fast math abs
		c=c<0? -c:c;
		c=c*140;
		// math max 255
		c=c>255?255:c;
		pix[i]=c<<16|c<<8|c;
	}
	canvas.setVector(canvas.rect, pix);
	canvas.unlock();
}

The above snippet will animate a gradient that looks like this: