Speaking of which, it would be nice if 3!:4 had options for converting unsigned numbers into J numbers. (It supports 2 byte numbers, but not other common sizes.)
Obviously, this would require picking a type of number which can represent the full range of values, but J has those types. -- Raul On Fri, Dec 30, 2011 at 1:15 PM, Raul Miller <rauldmil...@gmail.com> wrote: > That is ambiguous, in the general case. > > Practically speaking, however, it's defined by context. If the data > is "signed" the most significant bit is a "negative bit". If the data > is "unsigned" the most significant bit is a "binary digit". > > That said, some operations are useful regardless of this distinction > (which was the motivation for using this representation). For > example, if you have implemented addition, you can use the same > addition implementation for both "signed" and "unsigned" data. The > mechanics are the same, only the symbolism differs. > > -- > Raul > > On Thu, Dec 29, 2011 at 11:00 PM, Linda Alvord <lindaalv...@verizon.net> > wrote: >> How can you tell when the leading digit is a "negative bit" or a "binary >> digit"? >> >> In the situation above the same number can represent two different binary >> numbers. If 1 1 0 1 is sometimes 13 or might be _5 when is each >> appropriate?v. Isn't that the source of some problems? >> >> The spaces indicate that the number is probably a single binary number, but >> it could be a list of true and false indicators. You would need to know the >> context to determine the difference. >> >> Linda >> >> -----Original Message----- >> From: programming-boun...@jsoftware.com >> [mailto:programming-boun...@jsoftware.com] On Behalf Of Kip Murray >> Sent: Thursday, December 29, 2011 8:25 PM >> To: Programming forum >> Subject: Re: [Jprogramming] How #: should have been designed >> >> >> tcrRaul }: i:4 >> 1 0 0 >> 1 0 1 >> 1 1 0 >> 1 1 1 >> 0 0 0 >> 0 0 1 >> 0 1 0 >> 0 1 1 >> >> tcrRandy }: i:4 >> 1 1 0 0 >> 1 1 0 1 >> 1 1 1 0 >> 1 1 1 1 >> 0 0 0 0 >> 0 0 0 1 >> 0 0 1 0 >> 0 0 1 1 >> >> tcrRaul >> {.@#:@(,: (2 * >./@,)) >> >> tcrRandy >> (0 > ]) ,"0 1 #: >> >> >> On 12/29/2011 8:41 AM, Randy MacDonald wrote: >>> On 12/8/2011 4:39 PM, Raul Miller wrote: >>>> {.@#:@(,: 2 *>./@,)i:2 >>> ((0>]),"0 1#:) i:2 NB. seems to work just as well, and more obviously >>> handles the sign bit. >>> >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm >> >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
