spirit::karma::generate generates 10.0e-04, but expecting 1.0e-03

[markusjrmueller]

Code is:

std::string s;
double value = 0.00099999999999999829;
std::back_insert_iterator<std::string> sink(s);
boost::spirit::karma::generate(sink, boost::spirit::karma::real_generator<>(), value);
std::cout << s << std::endl; // outputs 10.0e-04

[hkaiser]

The 64 bit IEEE floating point format supports only up to 15.9 digits of precision (see https://en.wikipedia.org/wiki/Double-precision_floating-point_format). The number you are trying to convert requires at least 17 digits in order to be represented. The behavior of the generator is undefined in those cases. Please see #529 for more details.

[markusjrmueller]

I am using MSCV from visual studio 2017 in 64bit. The value comes out when doing some math. They claim to be IEEE conform when not compiling with the compiler flag /fast. At the moment I use the precise-flag.
I did tests with a precision of 6 and even changed the code according to #529 but nothing changes.
I do not know what I can do to fix this issue when using karma.

[hkaiser]

@markusjrmueller please see #629 for a possible fix. Please let us know if this resolves your issue.