JavaScript浮点运算，小数点精度

math.js

JavaScript浮点运算，小数点精度

// JavaScript Document
//数学函数
// 浮点数加法运算
function floatAdd(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;
}

// 浮点数减法运算
function floatSub(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));
        n = (r1 >= r2) ? r1 : r2;
        return ((arg1 * m - arg2 * m) / m).toFixed(n);
}

// 浮点数乘法运算
function floatMul(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);
}

// 浮点数除法运算
function floatDiv(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);
        }
}
// 设置数值精度
function setScale(value, scale, roundingMode) {
        if (roundingMode.toLowerCase() == "roundhalfup") {
                return (Math.round(value * Math.pow(10, scale)) / Math.pow(10, scale)).toFixed(scale);
        } else if (roundingMode.toLowerCase() == "roundup") {
                return (Math.ceil(value * Math.pow(10, scale)) / Math.pow(10, scale)).toFixed(scale);
        } else {
                return (Math.floor(value * Math.pow(10, scale)) / Math.pow(10, scale)).toFixed(scale);
        }
}