From: already5chosen@yahoo.com   
      
   On Tue, 6 Jan 2026 12:35:20 +0100   
   Terje Mathisen  wrote:   
      
   > Thomas Koenig wrote:   
   > > Michael S  schrieb:   
   > >> On Sun, 4 Jan 2026 00:21:31 -0000 (UTC)   
   > >> Thomas Koenig  wrote:   
   > >>   
   > >>>   
   > >>> And two decimal flavors, as well, with binary and densely packed   
   > >>> decimal encoding of the significand... it's a bit of a mess.   
   > >>>   
   > >>   
   > >> Since both formats have exactly identical semantics, in theory the   
   > >> mess is not worse (and not better) than two bytes orders of IEEE   
   > >> binary FP.   
   > >   
   > > Almost.   
   > >   
   > > IIRC, there is no restriction on the binary mantissa, so its   
   > > range is slightly larger for the same number of bits   
   > > (1000/1024)**(n/3).   
   > >   
   > Sorry, that's wrong:   
   >   
   > Just like the 24 "spare" DPD patterns are illegal,   
      
   Non-canonical, which is not the same as illegal   
   Silently accepted as input operands but never produced as result.   
      
   > any mantissa   
   > corresponding to a number greater than the maximum allowed (1e34   
   > afair) is also illegal, and there are rules for how to handle both   
   > cases (without checking, i seem to remember that they should be   
   > treated as zero?)   
   >   
      
   BID significand extension > max is indeed treated as zeros.   
   Non-canonical DPD declets have non-zero values.   
   They are forms of (8+c)*100 + (8+f)*10 + (8+i), where c, f, and i are   
   in range [0:1].   
      
   > Happy New Year everyone!   
   >   
   > Terje   
   >   
      
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