Oval - as from R Penner´s book

1

Hi!
I took following actionscript from R Penner´s book. But the oval which is drawn is not an oval, there is something wrong and I can´t see it.

 

MovieClip.prototype.drawOval=function(x, y, rx, ry){
 
this.moveTo (x+rx, y);
this.curveTo (rx+x, 0.4142*ry+y, 0.7071*rx+x, 0,7071*ry+y);
this.curveTo (0.4142*rx+x, ry+y, x, ry+y);
this.curveTo (-0.4142*rx+x, ry+y, -0.7071*rx+x, 0.7071*ry+y);
this.curveTo (-rx+x, 0.4142*ry+y, -rx+x, y);
this.curveTo (-rx+x, -0.4142*ry+y, -0.7071*rx+x, -0.7071*ry+y);
this.curveTo (-0.4142*rx+x, -ry+y, x, -ry+y);
this.curveTo (0.4142*rx+x, -ry+y, 0.7071*rx+x, -0.7071*ry+y);
this.curveTo (rx+x, -0.4142*ry+y, rx+x, y);

};
this.lineStyle (1, 0x00FF00);
this.drawOval (80, 100, 25, 15);