浮動小数点の足し算

function Float(){}
Float.add = function(a, b){
	var aa = (a + "").split("."), ab = (b + "").split(".")
		la = aa.length, lb = ab.length;
	if(la == 1 && lb == 1){
		return a + b;
	}
	if(la==1) aa.push("0");
	if(lb==1) ab.push("0");

	var d = Math.max(aa[1].length, ab[1].length);
	while(aa[1].length < d) aa[1] += "0";
	while(ab[1].length < d) ab[1] += "0";
	var ac = [], i, u = 0;
	for(i = d - 1; 0 <= i; i--){
		var n = (aa[1].substr(i, 1) - 0) + (ab[1].substr(i, 1) - 0) + u;
		u = 0;
		if(9 < n){
			n -= 10;
			u = 1;
		}
		ac.push(n);
	}
	var c = ((aa[0] - 0) + (ab[0] - 0) + u) + "." + ac.reverse().join("");
	return c - 0;
}