510380 - The number parser is naive and imprecise

Status: RESOLVED WONTFIX

(Tamarin Graveyard :: Virtual Machine, defect, P2)

Description

[Chris Peyer]

I am parsing a very large number (1e300) that comes in as a string (via socket connection). It seems to initialize a Number data type just fine, bot for some reason, it's not equal to a Number variable that was initialized with 1e300 directly. Also, the two variables print differently when passed to trace (as seen below).

Steps to reproduce:

var num1:Number = 1e300;
var num2:Number = Number("1e300");
trace(num1 == num2)
trace(num1);
trace(num2);
trace(num2-num1);
 
 Actual Results:

false
1e+300
1.00000000000000e+300
5.94806763391113e+284
 
 Expected Results:

true
1e+300
1e+300
0 

This bug transferred from: http://bugs.adobe.com/jira/browse/ASC-3693

Comment 1

[Lars T Hansen]

There are errors in the last places of the number returned by the number parser.  The number parser returns this value for 1e+300:

7e37e43c880075a0

whereas ASC produces this value for 1e+300:

7e37e43c8800759c

The underlying reason appears to be that the number parser does not implement the machinery that's necessary for avoiding this loss of precision.

Comment 3

[Lars T Hansen]

There is a little more information attached to bug #442273.  Specifically, we do not implement Clinger's algorithm for parsing floating-point algorithms, we use a naive algorithm that computes 1.0 and 10^300 and multiplies the two together.  To do better, we need to implement Clinger's algorithm.

Comment 4

[Steven Johnson]

Any fix for this bug will likely need version-checking for backwards compatibility.

Comment 5

[Michael Kohler [:mkohler]]

This is a mass change. Every comment has "assigned-to-new" in it.

I didn't look through the bugs, so I'm sorry if I change a bug which shouldn't be changed. But I guess these bugs are just bugs that were once assigned and people forgot to change the Status back when unassigning.

Comment 6

[Worcester12345]

Any update on this bug?

Comment 7

[Sylvestre Ledru [:Sylvestre]]

Tamarin is a dead project now. Mass WONTFIX.

Comment 8

[Sylvestre Ledru [:Sylvestre]]

Tamarin isn't maintained anymore. WONTFIX remaining bugs.