How to deal with Number precision in Actionscript?

Question

I have BigDecimal objects serialized with BlazeDS to Actionscript. Once they hit Actionscript as Number objects, they have values like:

140475.32 turns

Answer 1

You can use property: rounding = "nearest"

In NumberFormatter, rounding have 4 values which you can choice: rounding="none|up|down|nearest". I think with your situation, you can chose rounding = "nearest".

-- chary --

Answer 2

If you know the precision you need beforehand, you could store the numbers scaled so that the smallest amount you need is a whole value. For example, store the numbers as cents rather than dollars.

If that's not an option, how about something like this:

function printTwoDecimals(x)
{
   printWithNoDecimals(x);
   print(".");
   var scaled = Math.round(x * 100);
   printWithNoDecimals(scaled % 100);
}

(With however you print with no decimals stuck in there.)

This won't work for really big numbers, though, because you can still lose precision.

Answer 3

I converted the Java of BigDecimal to ActionScript. We had no choices since we compute for financial application.

http://code.google.com/p/bigdecimal/

Answer 4

It seems more like a transport problem, the number being correct but the scale ignored. If the number has to be stored as a BigDecimal on the server you may want to convert it server side to a less ambiguous format (Number, Double, Float) before sending it.

Answer 5

This is my generic solution for the problem (I have blogged about this here):

var toFixed:Function = function(number:Number, factor:int) {
  return Math.round(number * factor)/factor;
}

For example:

trace(toFixed(0.12345678, 10)); //0.1

• Multiply 0.12345678 by 10; that gives us 1.2345678.
• When we round 1.2345678, we get 1.0,
• and finally, 1.0 divided by 10 equals 0.1.

Another example:

trace(toFixed(1.7302394309234435, 10000)); //1.7302

• Multiply 1.7302394309234435 by 10000; that gives us 17302.394309234435.
• When we round 17302.394309234435 we get 17302,
• and finally, 17302 divided by 10000 equals 1.7302.

---

Edit

Based on the anonymous answer below, there is a nice simplification for the parameter on the method that makes the precision much more intuitive. e.g:

var setPrecision:Function = function(number:Number, precision:int) {
 precision = Math.pow(10, precision);
 return Math.round(number * precision)/precision;
}

var number:Number = 10.98813311;
trace(setPrecision(number,1)); //Result is 10.9
trace(setPrecision(number,2)); //Result is 10.98
trace(setPrecision(number,3)); //Result is 10.988 and so on

N.B. I added this here just in case anyone sees this as the answer and doesn't scroll down...

Answer 6

guys, just check the solution:

            protected function button1_clickHandler(event:MouseEvent):void
            {
                var formatter:NumberFormatter = new NumberFormatter();
                formatter.precision = 2;
                formatter.rounding = NumberBaseRoundType.NEAREST;
                var a:Number = 14.31999999999998;

                trace(formatter.format(a)); //14.32
            }