Hi, I looked at the patch and I guess it does not solve the problem.
The double value is still converted to long double, then to decimal and back to long double. Somewhere in this chain a rounding error increases the value slightly, that it is too large to fit into a double. The solution is to accept a slightly larger value than double max. If the value is just slightly bigger, it should be converted to double max. Tommi Am 24.07.2014 14:49, schrieb Martin Gansser: > --- Comment from Menanteau Guy --- > > I understood the problem of rounding error due to diffrent precision between > float and double but I don't see why not just process double as double instead > of float. > I did a patch to handle serialization double as double for casting and test is > succesfull now. Note that there was no need to create a new t_double type in > serializationinfo.h. > > Please could you have a look to the linked patch. > > https://bugzilla.redhat.com/attachment.cgi?id=920168 > >>> Gesendet: Montag, 07. Juli 2014 um 21:01 Uhr >>> Von: "Tommi Mäkitalo" <[email protected]> >>> An: [email protected] >>> Betreff: Re: [Tntnet-general] cxxtools-2.2.1-4.fc21 ppc64le - >>> std::numeric_limits<double>::max() returns 1.79769e+308 >>> Hi, >>> >>> The problem is a rounding error when converting double to decimal and back. >>> >>> The xmlserializer do not use scientific notation but converts floating >>> point values to decimal, so that the maximum double value results in >>> something like "17976900000000000000000000000000000000000000.....". >>> Internally long double is used in serialization and due to rounding >>> errors it may really happen, that the max double converted to long >>> double converted to a string and back to double max do exceed the range. >>> >>> The solution may be to accept slightly larger values than max-double. >>> >>> The actual code, which results in the error can be found in >>> include/cxxtools/serializationinfo.h and src/serializationinfo.cpp: >>> >>> serializationinfo.h: >>> >>> void getValue(double& value) const >>> { value = static_cast<double>(_getFloat("double", >>> std::numeric_limits<double>::max())); } >>> >>> serializationinfo.cpp: >>> long double SerializationInfo::_getFloat(const char* type, long double >>> max) const >>> { >>> ... >>> if (ret != std::numeric_limits<long double>::infinity() >>> && ret != -std::numeric_limits<long double>::infinity() >>> && ret == ret // check for NaN >>> && (ret < -max || ret > max)) >>> { >>> std::ostringstream msg; >>> msg << "value " << ret << " does not fit into " << type; >>> throw std::range_error(msg.str()); >>> } >>> >>> A possible fix is to change the acceptable limits of double to a >>> slightly larger value: >>> >>> serializationinfo.h: >>> >>> void getValue(double& value) const >>> { value = static_cast<double>(_getFloat("double", >>> static_cast<long >>> double>(std::numeric_limits<double>::max()))*1.0000000001); } >>> >>> The same should be done with float type. What do you think? >>> >>> Question: what happens, when a long double value is really too large and >>> it is casted to double? >>> >>> >>> Tommi >>> >>> >>> Am 07.07.2014 13:30, schrieb Martin Gansser: >>> Bug Report on: >>> https://bugzilla.redhat.com/show_bug.cgi?id=1108800[https://bugzilla.redhat.com/show_bug.cgi?id=1108800] >>> >>> >>> Description of problem: >>> running test (make check) of cxxtools package on ppc64le arch, I get an >>> error on test:xmlserializer::testDouble >>> problem occurs at testDoubleValue(std::numeric_limits<double>::max()); >>> value returned is 1.79769e+308 and later in the test following exception is >>> raised: >>> EXCEPTION: >>> value 1.79769e+308 does not fit into double >>> >>> Version-Release number of selected component (if applicable): >>> cxxtools-2.2.1-4.fc21 ppc64le >>> gcc-4.9.0-6.fc21 ppc64le >>> >>> Actual results: >>> xmlserializer::testDouble: EXCEPTION >>> value 1.79769e+308 does not fit into double >>> >>> Back to this problem, I understood value 1.79769e+308 is correct for the >>> maximum value of a type double. >>> This means the problem is not relative to gcc. I change component to >>> cxxtools for now. >>> >>> Is there any advice ? >>> > ------------------------------------------------------------------------------ > Want fast and easy access to all the code in your enterprise? Index and > search up to 200,000 lines of code with a free copy of Black Duck > Code Sight - the same software that powers the world's largest code > search on Ohloh, the Black Duck Open Hub! Try it now. > http://p.sf.net/sfu/bds > _______________________________________________ > Tntnet-general mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/tntnet-general ------------------------------------------------------------------------------ Want fast and easy access to all the code in your enterprise? Index and search up to 200,000 lines of code with a free copy of Black Duck Code Sight - the same software that powers the world's largest code search on Ohloh, the Black Duck Open Hub! Try it now. http://p.sf.net/sfu/bds _______________________________________________ Tntnet-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/tntnet-general
