重寫javascript浮點運算

javascript中變量存儲時不區分number和float類型,同一按照float存儲;

javascript使用IEEE 754-2008標準定義的64bit浮點格式存儲number,decimal64對應的整形部分長度爲10,小樹部分長度爲16;

javascript作小數點運算會出現不精準.

//加法運算
        var accAdd = function(num1,num2){
            var n1,n2,m;
            try{
                n1 = num1.toString().split(".")[1].length;
            }catch(e){
                n1 = 0;
            }
            try{
                n2 = num2.toString().split(".")[1].length;
            }catch(e){
                n2 = 0;
            }
            m = Math.pow(10,Math.max(n1,n2));
            return (num1*m + num2*m)/m;
        }

        //減法運算
        var suntr = function(num1,num2){
            var n1,n2,m,n;
            try{
                n1 = num1.toString().split(".")[1].length;
            }catch(e){
                n1 = 0;
            }
            try{
                n2 = num2.toString().split(".")[1].length;
            }catch(e){
                n2 = 0;
            }
            m = Math.pow(10,Math.max(n1,n2));
            n = (n1 > n2) ? n1 : n2;
            return ((num1*m - num2*m)/m).toFixed(n);
        }

        //乘法運算
        var accMul = function(num1,num2){
            var m = 0,n1,n2,
                s1 = num1.toString(),
                s2 = num2.toString();
            try{
                m += s1.split(".")[1].length;
            }catch(e){

            }
            try{
                m += s2.split(".")[1].length;
            }catch(e){

            }
            n1 = Number(s1.replace(".",""));
            n2 = Number(s2.replace(".",""));
            return n1 * n2 / Math.pow(10,m);
        }

        //除法運算
        var accDivi = function(num1,num2){
            var s1 = 0,s2 = 0,n1,n2;
            try{
                s1 = num1.toString().split(".")[1].length;
            }catch(e){

            }
            try{
                s2 = num2.toString().split(".")[1].length;
            }catch(e){

            }
            with(Math){
                n1 = Number(num1.toString().replace(".",""));
                n2 = Number(num2.toString().replace(".",""));
                return (n1/n2)*Math.pow(10,s2-s1);
            }
        }