-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 3/24/2011 02:29, Kai Tietz wrote: > 2011/3/23 James K Beard <[email protected]>: >> You don't need to go to BCD to convert DFP to IEEE (regular) floating point. >> A single arithmetic operation directly in DFP will exceed what you do to >> convert to IEEE floating point. I would use double precision for anything >> up to 12 decimals of accuracy, 80-bit for another three, and simply >> incorporate the quad precision libraries with credit (or by reference, if >> differences in licensing are a problem) for distribution. >> >> Anything other than binary representation will be less efficient in terms of >> accuracy provided by a given number of bits. By illustration, base 10 >> requires four bits, but provides only 3.32 bits (log2(10)) per digit of >> accuracy. The only relief from this fundamental fact is use of less bits >> for the exponent, and in IEEE floating point the size of the exponent field >> is minimized just about to the point of diminishing returns (problems >> requiring workaround in areas such as determinants, series and large >> polynomials) to begin with. >> >> James K Beard > > Well, DFP <-> IEEE conversion is already present in libgcc. So you > shouldn't need here any special implementation. I would suggest that > you are using for 32-bit and 64-bit DFP the double type, and AFAICS > the 80-bit IEEE should be wide enough for the 128-bit DFP. How big is > its exponent specified? Interesting might be the rounding. > > Regards, > Kai >
Long doubles extended precision go up to 4963 (base 10) in exponent, while DECIMAL128 go up 6144, this is assuming I didn't get the docs wrong. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (MingW32) iEYEARECAAYFAk2KnFEACgkQp56AKe10wHf30ACeKpD4YvTTR8k8pSO9njpa9pVQ /B8An1s6P6yNV1UcTdIe6evB6VrVz9IV =hBNq -----END PGP SIGNATURE-----
0xED74C077.asc
Description: application/pgp-keys
------------------------------------------------------------------------------ Enable your software for Intel(R) Active Management Technology to meet the growing manageability and security demands of your customers. Businesses are taking advantage of Intel(R) vPro (TM) technology - will your software be a part of the solution? Download the Intel(R) Manageability Checker today! http://p.sf.net/sfu/intel-dev2devmar
_______________________________________________ Mingw-w64-public mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mingw-w64-public
