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BigNumber //JavaScript Class

06.15.2006
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        <a href="http://jsfromhell.com/classes/bignumber">
Offers a extremely high precision level to make mathematical operations. For integers there is no limits and for floating point numbers, the class allows setting the maximum precision.

[UPDATED CODE AND HELP CAN BE FOUND HERE]

The class always returns new instances of BigNumber on the operations, so to the set value of a object, use the "set" method.
</a>

//+ Jonas Raoni Soares Silva
//@ http://jsfromhell.com/classes/bignumber [rev. #3]

BigNumber = function(n, p, r){
    var o = this, i;
    if(n instanceof BigNumber){
        for(i in {precision: 0, roundType: 0, _sign: 0, _dec: 0}) o[i] = n[i];
        o._buffer = n._buffer.slice();
        return;
    }
    o.precision = isNaN(p = Math.abs(p)) ? BigNumber.defaultPrecision : p;
    o.roundType = isNaN(r = Math.abs(r)) ? BigNumber.defaultRoundType : r;
    o._sign = (n += "").charAt(0) == "-";
    o._dec = ((n = n.replace(/[^\d.]/g, "").split(".", 2))[0] = n[0].replace(/^0+/, "") || "0").length;
    for(i = (n = o._buffer = (n.join("") || "0").split("")).length; i; n[--i] = +n[i]);
    o.round();
};
with({$: BigNumber, o: BigNumber.prototype}){
    $.ROUND_HALF_EVEN = ($.ROUND_HALF_DOWN = ($.ROUND_HALF_UP = ($.ROUND_FLOOR = ($.ROUND_CEIL = ($.ROUND_DOWN = ($.ROUND_UP = 0) + 1) + 1) + 1) + 1) + 1) + 1;
    $.defaultPrecision = 40;
    $.defaultRoundType = $.ROUND_HALF_UP;
    o.add = function(n){
        if(this._sign != (n = new BigNumber(n))._sign)
            return n._sign ^= 1, this.subtract(n);
        var o = new BigNumber(this), a = o._buffer, b = n._buffer, la = o._dec,
        lb = n._dec, n = Math.max(la, lb), i, r;
        la != lb && ((lb = la - lb) > 0 ? o._zeroes(b, lb, 1) : o._zeroes(a, -lb, 1));
        i = (la = a.length) == (lb = b.length) ? a.length : ((lb = la - lb) > 0 ? o._zeroes(b, lb) : o._zeroes(a, -lb)).length;
        for(r = 0; i; r = (a[--i] = a[i] + b[i] + r) / 10 >>> 0, a[i] %= 10);
        return r && ++n && a.unshift(r), o._dec = n, o.round();
    };
    o.subtract = function(n){
        if(this._sign != (n = new BigNumber(n))._sign)
            return n._sign ^= 1, this.add(n);
        var o = new BigNumber(this), c = o.abs().compare(n.abs()) + 1, a = c ? o : n, b = c ? n : o, la = a._dec, lb = b._dec, d = la, i, j;
        a = a._buffer, b = b._buffer, la != lb && ((lb = la - lb) > 0 ? o._zeroes(b, lb, 1) : o._zeroes(a, -lb, 1));
        for(i = (la = a.length) == (lb = b.length) ? a.length : ((lb = la - lb) > 0 ? o._zeroes(b, lb) : o._zeroes(a, -lb)).length; i;){
            if(a[--i] < b[i]){
                for(j = i; j && !a[--j]; a[j] = 9);
                --a[j], a[i] += 10;
            }
            b[i] = a[i] - b[i];
        }
        return c || (o._sign = n._sign), o._dec = d, o._buffer = b, o.round();
    };
    o.multiply = function(n){
        var o = new BigNumber(this), r = o._buffer.length >= (n = new BigNumber(n))._buffer.length, a = (r ? o : n)._buffer,
        b = (r ? n : o)._buffer, la = a.length, lb = b.length, x = new BigNumber, i, j, s;
        for(i = lb; i; r && s.unshift(r), x.set(x.add(new BigNumber(s.join("")))))
            for(s = (new Array(lb - --i)).join("0").split(""), r = 0, j = la; j; r += a[--j] * b[i], s.unshift(r % 10), r = (r / 10) >>> 0);
        return o._dec = ((r = la + lb - o._dec - n._dec) >= (j = (o._buffer = x._buffer).length) ? this._zeroes(o._buffer, r - j + 1, 1).length : j) - r, o.round();
    };
    o.divide = function(n){
        if((n = new BigNumber(n)) == "0")
            throw new Error("Division by 0");
        else if(this == "0")
            return new BigNumber;
        var o = new BigNumber(this), a = o._buffer, b = n._buffer, la = a.length - o._dec,
        lb = b.length - n._dec, r = new BigNumber, i = 0, j, s, last;
        r._sign = o._sign != n._sign, r.precision = Math.max(o.precision, n.precision),
        r._dec = +r._buffer.pop(), la != lb && o._zeroes(la > lb ? b : a, Math.abs(la - lb));
        n._dec = b.length, b = n, b._sign = false, b = b.round();
        for(n = new BigNumber; a[0] == "0"; a.shift());
        out:
        do{
            for(n == "0" && (n._buffer = [], n._dec = 0), last = 0; i < a.length && n.compare(b) == -1; ++i){
                if(last = i + 1 == a.length, n == "0" && a[i] == "0"){
                    if(r._dec == r._buffer.length && ++r._dec, r._buffer.push(0), last)
                        break out;
                }
                else if(n._buffer.push(a[i]), ++n._dec, (last && n.compare(b) == -1 && (r._dec == r._buffer.length && ++r._dec, 1)) || (last = 0))
                    do
                        r._buffer.push(0), n._buffer.push(0), ++n._dec;
                    while(n.compare(b) == -1);
            }
            if(n.compare(b) == -1 && !(last = 0))
                do
                    last ? r._buffer.push(0) : last = 1, n._buffer.push(0), ++n._dec;
                while(n.compare(b) == -1);
            for(s = new BigNumber, j = 0; n.compare(y = s.add(b)) + 1 && ++j; s.set(y));
            n.set(n.subtract(s)), !last && r._dec == r._buffer.length && ++r._dec, r._buffer.push(j);
        }
        while((i < a.length || n != "0") && (r._buffer.length - r._dec) <= r.precision);
        return r.round();
    };
    o.mod = function(n){
        return this.subtract(this.divide(n).intPart().multiply(n));
    };
    o.pow = function(n){
        var o = new BigNumber(this), i;
        if((n = (new BigNumber(n)).intPart()) == 0) return o.set(1);
        for(i = Math.abs(n); --i; o.set(o.multiply(this)));
        return n < 0 ? o.set((new BigNumber(1)).divide(o)) : o;
    };
    o.set = function(n){
        return this.constructor(n), this;
    };
    o.compare = function(n){
        var a = this, la = this._dec, b = new BigNumber(n), lb = b._dec, r = [-1, 1], i, l;
        if(a._sign != b._sign)
            return a._sign ? -1 : 1;
        if(la != lb)
            return r[(la > lb) ^ a._sign];
        for(la = (a = a._buffer).length, lb = (b = b._buffer).length, i = -1, l = Math.min(la, lb); ++i < l;)
            if(a[i] != b[i])
                return r[(a[i] > b[i]) ^ a._sign];
        return la != lb ? r[(la > lb) ^ a._sign] : 0;
    };
    o.negate = function(){
        var n = new BigNumber(this); return n._sign ^= 1, n;
    };
    o.abs = function(){
        var n = new BigNumber(this); return n._sign = 0, n;
    };
    o.intPart = function(){
        return new BigNumber((this._sign ? "-" : "") + (this._buffer.slice(0, this._dec).join("") || "0"));
    };
    o.valueOf = o.toString = function(){
        var o = this;
        return (o._sign ? "-" : "") + (o._buffer.slice(0, o._dec).join("") || "0") + (o._dec != o._buffer.length ? "." + o._buffer.slice(o._dec).join("") : "");
    };
    o._zeroes = function(n, l, t){
        var s = ["push", "unshift"][t || 0];
        for(++l; --l;  n[s](0));
        return n;
    };
    o.round = function(){
        if("_rounding" in this) return this;
        var $ = BigNumber, r = this.roundType, b = this._buffer, d, p, n, x;
        for(this._rounding = true; this._dec > 1 && !b[0]; --this._dec, b.shift());
        for(d = this._dec, p = this.precision + d, n = b[p]; b.length > d && !b[b.length -1]; b.pop());
        x = (this._sign ? "-" : "") + (p - d ? "0." + this._zeroes([], p - d - 1).join("") : "") + 1;
        if(b.length > p){
            n && (r == $.DOWN ? false : r == $.UP ? true : r == $.CEIL ? !this._sign
            : r == $.FLOOR ? this._sign : r == $.HALF_UP ? n >= 5 : r == $.HALF_DOWN ? n > 5
            : r == $.HALF_EVEN ? n >= 5 && b[p - 1] & 1 : false) && this.add(x);
            b.splice(p, b.length - p);
        }
        return delete this._rounding, this;
    };
}

Usage

<script type="text/javascript">

var x = new BigNumber("10"), y = new BigNumber("-2");
alert(x.pow(y));
alert(x.pow(1234));

alert((new BigNumber("99999999999999999999999999999999999")).add("999999999999999999999999999.99999999999999999"));

</script>
    

Comments

Snippets Manager replied on Sat, 2009/09/26 - 10:02pm

I've extended the class with the ability to convert between different numerical bases. I am willing to contribute it, please contact me at delorean.br [at] gmail.com.