function sub(arg1, arg2) {
        var r1, r2, m, n;
        try { r1 = arg1.toString().split('.')[1].length } catch (e) { r1 = 0 }
        try { r2 = arg2.toString().split('.')[1].length } catch (e) { r2 = 0 }
        m = Math.pow(10, Math.max(r1, r2));
        //动态控制精度长度
        n = (r1 >= r2) ? r1 : r2;
        return parseFloat(((arg1 * m - arg2 * m) / m).toFixed(n));
    }
    //加法
    function add(arg1, arg2) {
        var r1, r2, m;
        try { r1 = arg1.toString().split('.')[1].length } catch (e) { r1 = 0 }
        try { r2 = arg2.toString().split('.')[1].length } catch (e) { r2 = 0 }
        m = Math.pow(10, Math.max(r1, r2))
        return (arg1 * m + arg2 * m) / m
    }
    //乘法
    function mul(arg1, arg2) {
        var m = 0, s1 = arg1.toString(), s2 = arg2.toString();
        try { m += s1.split('.')[1].length } catch (e) { }
        try { m += s2.split('.')[1].length } catch (e) { }
        return Number(s1.replace('.', '')) * Number(s2.replace('.', '')) / Math.pow(10, m)
    }
    //除法
    function div(arg1, arg2) {
        var t1 = 0, t2 = 0, r1, r2;
        try { t1 = arg1.toString().split('.')[1].length } catch (e) { }
        try { t2 = arg2.toString().split('.')[1].length } catch (e) { }
        with (Math) {
            r1 = Number(arg1.toString().replace('.', ''))
            r2 = Number(arg2.toString().replace('.', ''))
            return (r1 / r2) * pow(10, t2 - t1);
        }
    }