gradient background using as3 code

var rect:Shape=new Shape();
this.addChild(rect);
rect.x = 0;
rect.y = 0;
var rectWidth:Number = 640;
var rectHeight:Number = 480;
var mat:Matrix;
var colors:Array;
var alphas:Array;
var ratios:Array;
mat=new Matrix();
colors = [0x000000,0x006699];
alphas = [1,1];
ratios = [0,255];
mat.createGradientBox(rectWidth,rectHeight,toRad(-90));
rect.graphics.lineStyle();
rect.graphics.beginGradientFill(GradientType.LINEAR,colors,alphas,ratios,mat);
rect.graphics.drawRect(0,0,rectWidth,rectHeight);
rect.graphics.endFill();
function toRad(a:Number):Number
{
return a*Math.PI/180;
}

Out put looks like :-