Archived:Data type 'long double' lacks precision on Symbian (Known Issue)
C++ code that uses the long double floating point data type might not have the desired precision when used on S60/Open C.
No known solution. Symbian does not support the long double data type, typically implemented as an 80-bit extended precision type. On Symbian, the TReal class (equivalent to double) 64-bit data type provides a range from about 2.225074 × 10–308 to about 1.797693 × 10+308, and an accuracy of 15 decimal places.