NaN handling bug in 1.1.3

[eichin]

(At europython, it was suggested that the forum is still the best place for bug reports...)

>>> lat = 0.0
>>> lon = 0.0
>>> math.atan2(lat,lon)
NaN
>>> 360.0*math.atan2(lat,lon)
** interpreter crashes **

number * NaN should be NaN (and is, in unix python.) While perhaps it could throw an exception (which wouldn't be right for IEEE math, but...) it shouldn't be making the interpreter die.

(This is on the 6630 phone itself, I don't know what it does in the emulator, as I develop on a Mac...)

I don't know if it's in 1.0 as well; computing bearings wasn't worthwhile before having Canvas :-)

[jplauril]

Originally posted by eichin
(At europython, it was suggested that the forum is still the best place for bug reports...)

>>> lat = 0.0
>>> lon = 0.0
>>> math.atan2(lat,lon)
NaN
>>> 360.0*math.atan2(lat,lon)
** interpreter crashes **

number * NaN should be NaN (and is, in unix python.) While perhaps it could throw an exception (which wouldn't be right for IEEE math, but...) it shouldn't be making the interpreter die.

(This is on the 6630 phone itself, I don't know what it does in the emulator, as I develop on a Mac...)

I don't know if it's in 1.0 as well; computing bearings wasn't worthwhile before having Canvas :-)

The specific exception is KERN-EXEC 3:

http://www.symbian.com/developer/tec...%2ekern%2dexec

According to http://tinyurl.com/bvczc we need to install an exception handler to handle attempting arithmetic with NaN's:

"Symbian OS also has special support for processor-level exceptions, such as division by zero. These are handled via the RThread class. Notice that if there is no exception handler in the thread and the thread raises an exception, the default implementation of the exception handler will panic with code KERN-EXEC 3."

We'll see what we can do. Thanks for the report.

[otsov]

Originally posted by jplauril

According to http://tinyurl.com/bvczc we need to install an exception handler to handle attempting arithmetic with NaN's:

Unfortunately this fix will not make it to the next release.

Here is a workaround with "CSPyInterpreter" which you can use for the time being:

1) Embed the interpreter in your native C++ application;
2) Install an exception handler to your native application (in the thread where you create the "CSPyInterpreter" instance).

Check these threads:

http://discussion.forum.nokia.com/fo...threadid=55828
http://discussion.forum.nokia.com/fo...threadid=58377

Adding the exception handler, see this link:

http://www3.symbian.com/faq.nsf/0/A1...B?OpenDocument

So, these lines will be needed:

Handler:

static void handler(TExcType /*aType*/)
{
// do nothing
}

and adding it:

RThread().SetExceptionHandler(handler,KExceptionFpe);

Will result in 6600:

Python 2.2.2 (#0, Jun 28 2005, 14:26:52)
[GCC 2.9-psion-98r2 (Symbian build 546)] on symbian_s60
Type "copyright", "credits" or "license" for more information.
Type "commands" to see the commands available in this simple line editor.
>>> import math
>>> lat = 0.0
>>> lon = 0.0
>>> math.atan2(lat,lon)
NaN
>>> 360.0*math.atan2(lat,lon)
NaN
>>>

[jplauril]

For reference: tracking number for this bug is #208.