Re: [Flashcoders] problem with adding two digits

[Anthony Pace]

to prevent anyone answering on this thread:
after toying with it again, and reading the docs + wikipedia I figured 
out that I can only trust a result of 15 digits or less, unless I have 
the string be returned instead of the number.


n 12/18/2010 8:34 PM, Anthony Pace wrote:


function floatSumV3(roundDown:Boolean = true, ... nums):Number{
var nl:uint = nums.length;
var ls:Number=0; //left side
var pp:int; //period position
var rs:Number = 1; //right side
var rsl:int; //right side length
var ml:int = 0; //max length right side
var powerCounter:int = 1;
var powerResult:int;
var s:String;
for (var i:int = 0; i< nl; ++i) {
s = nums[i].toString();
pp = s.indexOf('.');
if(pp!=-1){
rsl = s.length - pp-1;
if(rsl>ml){
p


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Re: [Flashcoders] problem with adding two digits

[Anthony Pace]

whoa... hold on Help Please.

After I posted yesterday, (or the night before??? can't remember) as I 
realized how badly the code sucked, I was just messing around with this 
code below to see if I could separate the halves and recompose them 
properly; however,

if you pop the code below on the timeline, you will see why I am confused.

I know it's not the greatest piece of code in the world, especially 
since I was just messing around mentally, but it should work.  Why is 
the process of converting to a Number adding .1


function floatSumV3(roundDown:Boolean = true, ... nums):Number{
var nl:uint = nums.length;
var ls:Number=0; //left side
var pp:int; //period position
var rs:Number = 1; //right side
var rsl:int; //right side length
var ml:int = 0; //max length right side
var powerCounter:int = 1;
var powerResult:int;
var s:String;
for (var i:int = 0; i< nl; ++i) {
s = nums[i].toString();
pp = s.indexOf('.');
if(pp!=-1){
rsl = s.length - pp-1;
if(rsl>ml){
powerCounter = rsl - ml;
powerResult=1;
while(powerCounter!=0){
powerResult *= 10;
powerCounter -= 1;
}
rs *= powerResult;
rs += Number(s.substr(pp+1));
ml=rsl;
//trace('ml = '+ml+', rs = '+ rs);
}else if (rslare production ready.


Also, I would only use these if you will know that the numbers past 
the mantissa are of small amounts.


Oh yeah, and please tell me if I screwed up somewhere, or if you 
think you can do it better :)


function floatProduct(... nums){
var ml:int = 0; //max length past mantissa
var ln:uint = nums.length;
var rsl:int; //right side length
var p:Number = 1;
var s:String;
for (var i:uint = 0; i< ln; ++i) {
s = nums[i].toString();
rsl = s.length - s.indexOf('.');
ml += rsl;
p *= nums[i];
}
return Number(p.toFixed(ml));
}
function floatSum(... nums){
var ml:int = 0; //max length past mantissa
var ln:uint = nums.length;
var rsl:int; //right side length
var p:Number = 0;
var s:String;
for (var i:int = 0; i< ln; ++i) {
s = nums[i].toString();
rsl = s.length - s.indexOf('.');
if (rsl > ml) {
ml = rsl;
}
p += nums[i];
}
return Number(p.toFixed(ml));
}


-




On 12/14/2010 12:05 PM, Kerry Thompson wrote:

Adrian Zając wrote:



trace (0.27 + 0.03);   // output -->  0.30004

Can anyone tell me why I get this weird result in output window?


As people have said, it's a problem with decimals. It's not a 
problem with

Flash--it's a problem with binary numbers.

Integers are accurate because all integers are a multiple of 1, and 
binary
does just fine with combining 0's and 1's, the only possibile values 
of a

digit in the binary system.

If you think of decimals as fractions, maybe it will help you 
understand the
issue. In binary, a digit can only be a multiple of 2: 1/2, 1/4, 
1/8/ 1/16,

1/32, and so on. You can create numbers that aren't multiples of two by
adding multiple digits. For example, 1/4 + 1/8 = 3/8, or .375.

This works pretty well, until you get numbers with a lot of decimal 
places.

At some point, you will find a decimal that is impossible to make using
powers of 2.

Cordially,

Kerry Thompson
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Re: [Flashcoders] problem with adding two digits

[Anthony Pace]

Oh yeah, I forgot to give some examples to test it with, so...

trace(floatSum(-0.1,0.9155,0.1,0.1,0.1,0.1,0.1,0.1,0.1,0.1));
//vs
trace(-0.1+0.9155+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1);
//and
trace(floatProduct(2.1,0.1,1.0001,.0001));
//vs
trace(2.1*0.1*1.0001*.0001);


On 12/15/2010 2:25 PM, Anthony Pace wrote:
I wrote the functions below in literally just a few min, so, even 
though they do seem to work for me, I wouldn't necessarily say they 
are production ready.


Also, I would only use these if you will know that the numbers past 
the mantissa are of small amounts.


Oh yeah, and please tell me if I screwed up somewhere, or if you think 
you can do it better :)


function floatProduct(... nums){
var ml:int = 0; //max length past mantissa
var ln:uint = nums.length;
var rsl:int; //right side length
var p:Number = 1;
var s:String;
for (var i:uint = 0; i< ln; ++i) {
s = nums[i].toString();
rsl = s.length - s.indexOf('.');
ml += rsl;
p *= nums[i];
}
return Number(p.toFixed(ml));
}
function floatSum(... nums){
var ml:int = 0; //max length past mantissa
var ln:uint = nums.length;
var rsl:int; //right side length
var p:Number = 0;
var s:String;
for (var i:int = 0; i< ln; ++i) {
s = nums[i].toString();
rsl = s.length - s.indexOf('.');
if (rsl > ml) {
ml = rsl;
}
p += nums[i];
}
return Number(p.toFixed(ml));
}


-




On 12/14/2010 12:05 PM, Kerry Thompson wrote:

Adrian Zając wrote:



trace (0.27 + 0.03);   // output -->  0.30004

Can anyone tell me why I get this weird result in output window?


As people have said, it's a problem with decimals. It's not a problem 
with

Flash--it's a problem with binary numbers.

Integers are accurate because all integers are a multiple of 1, and 
binary
does just fine with combining 0's and 1's, the only possibile values 
of a

digit in the binary system.

If you think of decimals as fractions, maybe it will help you 
understand the
issue. In binary, a digit can only be a multiple of 2: 1/2, 1/4, 1/8/ 
1/16,

1/32, and so on. You can create numbers that aren't multiples of two by
adding multiple digits. For example, 1/4 + 1/8 = 3/8, or .375.

This works pretty well, until you get numbers with a lot of decimal 
places.

At some point, you will find a decimal that is impossible to make using
powers of 2.

Cordially,

Kerry Thompson
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Re: [Flashcoders] problem with adding two digits

[Anthony Pace]

I wrote the functions below in literally just a few min, so, even though 
they do seem to work for me, I wouldn't necessarily say they are 
production ready.


Also, I would only use these if you will know that the numbers past the 
mantissa are of small amounts.


Oh yeah, and please tell me if I screwed up somewhere, or if you think 
you can do it better :)


function floatProduct(... nums){
var ml:int = 0; //max length past mantissa
var ln:uint = nums.length;
var rsl:int; //right side length
var p:Number = 1;
var s:String;
for (var i:uint = 0; i< ln; ++i) {
s = nums[i].toString();
rsl = s.length - s.indexOf('.');
ml += rsl;
p *= nums[i];
}
return Number(p.toFixed(ml));
}
function floatSum(... nums){
var ml:int = 0; //max length past mantissa
var ln:uint = nums.length;
var rsl:int; //right side length
var p:Number = 0;
var s:String;
for (var i:int = 0; i< ln; ++i) {
s = nums[i].toString();
rsl = s.length - s.indexOf('.');
if (rsl > ml) {
ml = rsl;
}
p += nums[i];
}
return Number(p.toFixed(ml));
}


-




On 12/14/2010 12:05 PM, Kerry Thompson wrote:

Adrian Zając wrote:



trace (0.27 + 0.03);   // output -->  0.30004

Can anyone tell me why I get this weird result in output window?


As people have said, it's a problem with decimals. It's not a problem with
Flash--it's a problem with binary numbers.

Integers are accurate because all integers are a multiple of 1, and binary
does just fine with combining 0's and 1's, the only possibile values of a
digit in the binary system.

If you think of decimals as fractions, maybe it will help you understand the
issue. In binary, a digit can only be a multiple of 2: 1/2, 1/4, 1/8/ 1/16,
1/32, and so on. You can create numbers that aren't multiples of two by
adding multiple digits. For example, 1/4 + 1/8 = 3/8, or .375.

This works pretty well, until you get numbers with a lot of decimal places.
At some point, you will find a decimal that is impossible to make using
powers of 2.

Cordially,

Kerry Thompson
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Re: [Flashcoders] problem with adding two digits

[Kerry Thompson]

Adrian Zając wrote:


>trace (0.27 + 0.03);   // output --> 0.30004
>
> Can anyone tell me why I get this weird result in output window?


As people have said, it's a problem with decimals. It's not a problem with
Flash--it's a problem with binary numbers.

Integers are accurate because all integers are a multiple of 1, and binary
does just fine with combining 0's and 1's, the only possibile values of a
digit in the binary system.

If you think of decimals as fractions, maybe it will help you understand the
issue. In binary, a digit can only be a multiple of 2: 1/2, 1/4, 1/8/ 1/16,
1/32, and so on. You can create numbers that aren't multiples of two by
adding multiple digits. For example, 1/4 + 1/8 = 3/8, or .375.

This works pretty well, until you get numbers with a lot of decimal places.
At some point, you will find a decimal that is impossible to make using
powers of 2.

Cordially,

Kerry Thompson
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Re: [Flashcoders] problem with adding two digits

[Adrian Zając]

Thanks Zeh, now I understand.

So do we have to keep an eye on our variables so we don't have for 
example:7.998 * 0,3004  ?
Because I think it is a little heavier for processors to count than:  8 
* 0.3



W dniu 2010-12-14 16:36, Zeh Fernando pisze:

I like to quote this, from PHP.net's "Floating Point" documentation:

"Floating point numbers have limited precision. Although it depends on the
system, PHP typically uses the IEEE 754 double precision format, which will
give a maximum relative error due to rounding in the order of 1.11e-16. Non
elementary arithmetic operations may give larger errors, and, of course,
error propagation must be considered when several operations are compounded.

Additionally, rational numbers that are exactly representable as floating
point numbers in base 10, like 0.1 or 0.7, do not have an exact
representation as floating point numbers in base 2, which is used
internally, no matter the size of the mantissa. Hence, they cannot be
converted into their internal binary counterparts without a small loss of
precision. This can lead to confusing results: for example,
floor((0.1+0.7)*10) will usually return 7 instead of the expected 8, since
the internal representation will be something like 7.9991118

So never trust floating number results to the last digit, and never compare
floating point numbers for equality."

Additional, interesting read:
http://en.wikipedia.org/wiki/Floating_point#Accuracy_problems

On Tue, Dec 14, 2010 at 10:15 AM, tom rhodes  wrote:

   

same here compiling for flash player 10 and flash player 9, 8 and below
give
0.3 as expected


On 14 December 2010 15:42, Adrian Zając  wrote:

 

trace (0.27 + 0.03);
   

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Re: [Flashcoders] problem with adding two digits

[Henrik Andersson]

tom rhodes skriver:

yup interesting that the old AVM gives you what you'd think...


Pure luck, you might have compiled against something that happened to 
drop the decimal instead .


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Re: [Flashcoders] problem with adding two digits

[tom rhodes]

yup interesting that the old AVM gives you what you'd think...


On 14 December 2010 16:36, Zeh Fernando  wrote:

> I like to quote this, from PHP.net's "Floating Point" documentation:
>
> "Floating point numbers have limited precision. Although it depends on the
> system, PHP typically uses the IEEE 754 double precision format, which will
> give a maximum relative error due to rounding in the order of 1.11e-16. Non
> elementary arithmetic operations may give larger errors, and, of course,
> error propagation must be considered when several operations are
> compounded.
>
> Additionally, rational numbers that are exactly representable as floating
> point numbers in base 10, like 0.1 or 0.7, do not have an exact
> representation as floating point numbers in base 2, which is used
> internally, no matter the size of the mantissa. Hence, they cannot be
> converted into their internal binary counterparts without a small loss of
> precision. This can lead to confusing results: for example,
> floor((0.1+0.7)*10) will usually return 7 instead of the expected 8, since
> the internal representation will be something like
> 7.9991118
>
> So never trust floating number results to the last digit, and never compare
> floating point numbers for equality."
>
> Additional, interesting read:
> http://en.wikipedia.org/wiki/Floating_point#Accuracy_problems
> 
> On Tue, Dec 14, 2010 at 10:15 AM, tom rhodes  wrote:
>
> > same here compiling for flash player 10 and flash player 9, 8 and below
> > give
> > 0.3 as expected
> >
> >
> > On 14 December 2010 15:42, Adrian Zając  wrote:
> >
> > > trace (0.27 + 0.03);
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Re: [Flashcoders] problem with adding two digits

[John R. Sweeney Jr]

Howdy Adrian,

Here is one way.

trace (int((0.27 + 0.03)*100)/100)   // output -->  0.3


Later,
John


on 12/14/10 8:42 AM, Adrian Zając at zajac.adr...@gmail.com wrote:

> Hello,
> 
> First of all, I want to say Hi to everyone here. This is my first post.
> 
> 
> Please, take a look at this part of code:
> 
>  trace (0.27 + 0.03);   // output --> 0.30004
> 
> Can anyone tell me why I get this weird result in output window?
> 
> 
> Regards
> Adrian


John R. Sweeney Jr.
Interactive Multimedia Developer


OnDemand Interactive Inc
945 Washington Blvd.
Hoffman Estates, IL 60169
Office/Fax: 847.310.5959
Cellular: 847.651.4469
www.ondemandinteractive.com



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Re: [Flashcoders] problem with adding two digits

[Zeh Fernando]

I like to quote this, from PHP.net's "Floating Point" documentation:

"Floating point numbers have limited precision. Although it depends on the
system, PHP typically uses the IEEE 754 double precision format, which will
give a maximum relative error due to rounding in the order of 1.11e-16. Non
elementary arithmetic operations may give larger errors, and, of course,
error propagation must be considered when several operations are compounded.

Additionally, rational numbers that are exactly representable as floating
point numbers in base 10, like 0.1 or 0.7, do not have an exact
representation as floating point numbers in base 2, which is used
internally, no matter the size of the mantissa. Hence, they cannot be
converted into their internal binary counterparts without a small loss of
precision. This can lead to confusing results: for example,
floor((0.1+0.7)*10) will usually return 7 instead of the expected 8, since
the internal representation will be something like 7.9991118

So never trust floating number results to the last digit, and never compare
floating point numbers for equality."

Additional, interesting read:
http://en.wikipedia.org/wiki/Floating_point#Accuracy_problems

On Tue, Dec 14, 2010 at 10:15 AM, tom rhodes  wrote:

> same here compiling for flash player 10 and flash player 9, 8 and below
> give
> 0.3 as expected
>
>
> On 14 December 2010 15:42, Adrian Zając  wrote:
>
> > trace (0.27 + 0.03);
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Re: [Flashcoders] problem with adding two digits

[Karim Beyrouti]

It's an issue with floating point accuracy/calculations, 

Here is some info:
http://joshblog.net/2007/01/30/flash-floating-point-number-errors/
saw more about it somewhere else... don't think it's an issue with the FP tho'.


- Karim

On 14 Dec 2010, at 15:15, tom rhodes wrote:

> same here compiling for flash player 10 and flash player 9, 8 and below give
> 0.3 as expected
> 
> 
> On 14 December 2010 15:42, Adrian Zając  wrote:
> 
>> trace (0.27 + 0.03);
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Re: [Flashcoders] problem with adding two digits

[Adrian Zając]

If you need the addition to be accurate and you know that the numbers will 
always be decimals you can multiply the numbers by 100 and then you will add 27 
+ 3 which  will return 30 and then divide it by 100 to get your .3 (or at least 
I think that will work as I have not tried it)
   


Yes Steve, probably this is the best solution. But still I want to know 
why is it working in that way.

Funny thing with  flash player versions...  Tom, thanks for checking it out.


W dniu 2010-12-14 16:15, tom rhodes pisze:

same here compiling for flash player 10 and flash player 9, 8 and below give
0.3 as expected


On 14 December 2010 15:42, Adrian Zając  wrote:

   

trace (0.27 + 0.03);
 

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Re: [Flashcoders] problem with adding two digits

[tom rhodes]

same here compiling for flash player 10 and flash player 9, 8 and below give
0.3 as expected


On 14 December 2010 15:42, Adrian Zając  wrote:

> trace (0.27 + 0.03);
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RE: [Flashcoders] problem with adding two digits

[Steve Abaffy]

It has to do with the fact that computers have to convert all numbers to binary 
then perform math on those numbers and then convert back to decimal. In the 
process of this conversion you get results like these.

If you need the addition to be accurate and you know that the numbers will 
always be decimals you can multiply the numbers by 100 and then you will add 27 
+ 3 which  will return 30 and then divide it by 100 to get your .3 (or at least 
I think that will work as I have not tried it)

-Original Message-
From: flashcoders-boun...@chattyfig.figleaf.com 
[mailto:flashcoders-boun...@chattyfig.figleaf.com] On Behalf Of Adrian Zajac
Sent: Tuesday, December 14, 2010 8:43 AM
To: Flash Coders List
Subject: [Flashcoders] problem with adding two digits

Hello,

First of all, I want to say Hi to everyone here. This is my first post.


Please, take a look at this part of code:

 trace (0.27 + 0.03);   // output --> 0.30004

Can anyone tell me why I get this weird result in output window?


Regards
Adrian
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