(10-24-2015 12:48 PM)retoa Wrote: So the prime uses a 48 bits mantissa to work with binary floating point, and not 52 like in IEEE 754 double precision. How will be a number represented?

I mean in double precision you have 1 bit for the sign, 11 for the exponent and 52 for the mantissa. What about the Prime? If it works with 64 bits and the mantissa is truncated from 52 to 48 what are the 4 "missing" bits used for?

Actually normalized floats have 53 bits of mantissa because the initial bit is always 1 hence not stored. There are 5 bits that are reserved in the giac::gen data for the type field, and the 48 remaining ones are for mantissa. The 5 missing bits are truncated to 0.