drawSemiCircle(ctx, x, y, radius){
			ctx.beginPath();
			ctx.arc(x, y, radius, 0, Math.PI, false);
			ctx.moveTo(x - radius, y);
			ctx.lineTo(x + radius, y);
			ctx.stroke();
		}

		var data1 = [
			[1,1,.5,.1,.3],
			[2,2,.3,.5,.2],
			[3,3,.9,.5,.2],
			[1.5,-.05,.5,.1,.3],
			[3.15,1.,.5,.1,.3],
			[2.5,-1.,.5,.1,.3]
		];

		var data1_points = {
			show: true,
			radius: 5,
			fillColor: "blue", 
			errorbars: "xy", 
			xerr: {show: true, asymmetric: true, upperCap: "-", lowerCap: "-"}, 
			yerr: {show