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Re: Big integers

From jacobnavia <jacob@jacob.remcomp.fr>
Newsgroups comp.lang.c
Subject Re: Big integers
Date 2018-12-05 20:03 +0100
Organization A noiseless patient Spider
Message-ID <pu97ep$rqp$1@dont-email.me> (permalink)
References <YfuND.286973$lKb.275890@fx15.am4> <01c809d8-12f2-4755-8207-a000f1d6c9c1@googlegroups.com> <%VyND.512769$p%6.229167@fx26.am4> <pu7031$1d82$1@gioia.aioe.org> <pu935q$dsq$1@news.albasani.net>

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Le 05/12/2018 à 18:50, Jens Stuckelberger a écrit :
> On Tue, 04 Dec 2018 23:45:56 +0100, jacob navia wrote:
> 
>> Each number is 64 bytes, where the first 32 are the sign (I know is
>> wasteful but it is faster than using only one bit)
> 
> 	That would not be wasteful - it would be crazy. One must assume
> you mean bits - which is wasteful indeed.
> 

What is "wasteful"?

This is wasteful of space but spares time consuming masking operations.

Several options are available for the first 64 bits:

1: Sign 32 bits, biased exponent 32 bits. This is the one I use.
2: Sign 1 bit, biased exponent 31 bits, followed by 32 bits of data.
That would allow for fast tests for negative since the sign bit could be 
tested by testing for a negative 64 bit number, a single instruction.
Exponent access would be more involved since the sign bit must be masked
away. That would be fairly fast, but now the handling of the first 32 
bits would have to be special since all numbers are assumed base 2^64 
and the first would be base 2^32.
This could be done of course (just zero extend those 32 bits, but you 
would need intermediate storage for the first number... etc etc)

So, I decided to waste some space.

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Big integers Bart <bc@freeuk.com> - 2018-12-04 12:17 +0000
  Re: Big integers fir <profesor.fir@gmail.com> - 2018-12-04 05:58 -0800
    Re: Big integers Chad <cdalten@gmail.com> - 2018-12-04 08:22 -0800
      Re: Big integers Bart <bc@freeuk.com> - 2018-12-04 17:04 +0000
        Re: Big integers scott@slp53.sl.home (Scott Lurndal) - 2018-12-04 17:19 +0000
  Re: Big integers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-12-04 08:38 -0800
    Re: Big integers Bart <bc@freeuk.com> - 2018-12-04 17:35 +0000
      Re: Big integers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-04 18:13 +0000
        Re: Big integers "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2018-12-04 10:50 -0800
        Re: Big integers Rosario19 <Ros@invalid.invalid> - 2018-12-06 17:56 +0100
      Re: Big integers Thiago Adams <thiago.adams@gmail.com> - 2018-12-04 10:22 -0800
        Re: Big integers Eli the Bearded <*@eli.users.panix.com> - 2018-12-04 18:58 +0000
          Re: Big integers Thiago Adams <thiago.adams@gmail.com> - 2018-12-04 11:32 -0800
            Re: Big integers Eli the Bearded <*@eli.users.panix.com> - 2018-12-04 22:45 +0000
              Re: Big integers jameskuyper@alumni.caltech.edu - 2018-12-04 14:57 -0800
          Re: Big integers jameskuyper@alumni.caltech.edu - 2018-12-04 12:14 -0800
          Re: Big integers chris.m.thomasson.1@gmail.com - 2018-12-04 16:58 -0800
            Re: Big integers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-05 03:14 +0000
              Re: Big integers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-12-05 14:27 -0800
            Re: Big integers Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2018-12-04 20:03 -0500
              Re: Big integers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-12-05 14:25 -0800
      Re: Big integers jacob navia <jacob@jacob.remcomp.fr> - 2018-12-04 23:45 +0100
        Re: Big integers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-04 23:29 +0000
        Re: Big integers Bart <bc@freeuk.com> - 2018-12-05 00:30 +0000
          Re: Big integers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-12-05 14:28 -0800
        Re: Big integers Jens Stuckelberger <Jens_Stuckelberger@nowhere.net> - 2018-12-05 17:50 +0000
          Re: Big integers jacobnavia <jacob@jacob.remcomp.fr> - 2018-12-05 20:03 +0100
        Re: Big integers Keith Thompson <kst-u@mib.org> - 2018-12-05 13:46 -0800
          Re: Big integers jacobnavia <jacob@jacob.remcomp.fr> - 2018-12-06 06:41 +0100
            Re: Big integers Keith Thompson <kst-u@mib.org> - 2018-12-05 22:40 -0800
  Re: Big integers "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2018-12-04 09:08 -0800
    Re: Big integers Bart <bc@freeuk.com> - 2018-12-04 19:41 +0000
      Re: Big integers "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2018-12-04 12:00 -0800
    Re: Big integers Bart <bc@freeuk.com> - 2018-12-08 11:28 +0000
  Re: Big integers Ian Collins <ian-news@hotmail.com> - 2018-12-05 15:19 +1300
    Re: Big integers Bart <bc@freeuk.com> - 2018-12-05 11:58 +0000
      Re: Big integers David Brown <david.brown@hesbynett.no> - 2018-12-05 14:35 +0100
        Re: Big integers Bart <bc@freeuk.com> - 2018-12-05 14:35 +0000
          Re: Big integers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-12-05 07:39 -0800
            Re: Big integers Thiago Adams <thiago.adams@gmail.com> - 2018-12-05 07:45 -0800
              Re: Big integers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-05 17:51 +0000
                Re: Big integers David Brown <david.brown@hesbynett.no> - 2018-12-05 22:19 +0100
              Re: Big integers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-12-05 14:55 -0800
                Re: Big integers jameskuyper@alumni.caltech.edu - 2018-12-05 15:19 -0800
                Re: Big integers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-12-05 16:13 -0800
                Re: Big integers David Brown <david.brown@hesbynett.no> - 2018-12-06 09:35 +0100
                Re: Big integers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-12-07 14:26 -0800
                Re: Big integers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-12-07 19:56 -0800
                Re: Big integers James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-09 12:01 -0500
                Re: Big integers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-12-10 14:47 -0800
                Re: Big integers scott@slp53.sl.home (Scott Lurndal) - 2018-12-11 00:50 +0000
                Re: Big integers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-12-10 17:37 -0800
                Re: Big integers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-12-14 21:18 -0800
          Re: Big integers Thiago Adams <thiago.adams@gmail.com> - 2018-12-05 07:57 -0800
          Re: Big integers Bart <bc@freeuk.com> - 2018-12-05 15:59 +0000
            Re: Big integers Bart <bc@freeuk.com> - 2018-12-05 22:59 +0000
              Re: Big integers jameskuyper@alumni.caltech.edu - 2018-12-05 15:31 -0800
                Re: Big integers Robert Wessel <robertwessel2@yahoo.com> - 2018-12-05 20:03 -0600
              Re: Big integers scott@slp53.sl.home (Scott Lurndal) - 2018-12-05 23:42 +0000
                Re: Big integers James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-05 20:15 -0500
              Re: Big integers Ike Naar <ike@iceland.freeshell.org> - 2018-12-10 07:26 +0000
                Re: Big integers Bart <bc@freeuk.com> - 2018-12-10 18:38 +0000
                Re: Big integers scott@slp53.sl.home (Scott Lurndal) - 2018-12-10 19:10 +0000
                Re: Big integers Bart <bc@freeuk.com> - 2018-12-10 21:23 +0000
                Re: Big integers Ike Naar <ike@iceland.freeshell.org> - 2018-12-10 22:47 +0000
          Re: Big integers David Brown <david.brown@hesbynett.no> - 2018-12-05 22:15 +0100
        Re: Big integers Bart <bc@freeuk.com> - 2018-12-06 13:43 +0000
          Re: Big integers Thiago Adams <thiago.adams@gmail.com> - 2018-12-06 07:50 -0800
      Re: Big integers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-05 15:19 +0000
        Re: Big integers luser droog <luser.droog@gmail.com> - 2018-12-10 23:19 -0800
          Re: Big integers David Brown <david.brown@hesbynett.no> - 2018-12-11 08:45 +0100
            Re: Big integers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-11 11:15 +0000
              Re: Big integers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-12-11 04:36 -0800
                Re: Big integers David Brown <david.brown@hesbynett.no> - 2018-12-11 14:35 +0100
              Re: Modules again (was: Big integers) Bart <bc@freeuk.com> - 2018-12-11 12:53 +0000
                Re: Modules again David Brown <david.brown@hesbynett.no> - 2018-12-11 14:45 +0100
                Re: Modules again Bart <bc@freeuk.com> - 2018-12-11 16:08 +0000
                Re: Modules again David Brown <david.brown@hesbynett.no> - 2018-12-11 21:37 +0100
                Re: Modules again Thiago Adams <thiago.adams@gmail.com> - 2018-12-11 08:59 -0800
                Re: Modules again Bart <bc@freeuk.com> - 2018-12-11 17:49 +0000
                Re: Modules again David Brown <david.brown@hesbynett.no> - 2018-12-11 21:44 +0100
                Re: Modules again scott@slp53.sl.home (Scott Lurndal) - 2018-12-11 18:02 +0000
                Re: Modules again Thiago Adams <thiago.adams@gmail.com> - 2018-12-11 10:10 -0800
                Re: Modules again scott@slp53.sl.home (Scott Lurndal) - 2018-12-11 18:54 +0000
                Re: Modules again Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2018-12-11 13:14 -0500
                Re: Modules again scott@slp53.sl.home (Scott Lurndal) - 2018-12-11 18:54 +0000
                Re: Modules again Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2018-12-11 14:42 -0500
                Re: Modules again David Brown <david.brown@hesbynett.no> - 2018-12-11 21:54 +0100
                Re: Modules again Keith Thompson <kst-u@mib.org> - 2018-12-11 14:53 -0800
                Re: Modules again David Brown <david.brown@hesbynett.no> - 2018-12-12 08:24 +0100
                Re: Modules again David Brown <david.brown@hesbynett.no> - 2018-12-11 21:51 +0100
                Re: Modules again scott@slp53.sl.home (Scott Lurndal) - 2018-12-11 23:24 +0000
                Re: Modules again Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2018-12-11 18:44 -0500
                Re: Modules again Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2018-12-11 18:45 -0500
                Re: Modules again Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-12-12 06:39 +0000
                Re: Modules again James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-12 07:59 -0500
                Re: Modules again mark.bluemel@gmail.com - 2018-12-12 05:43 -0800
                Re: Modules again scott@slp53.sl.home (Scott Lurndal) - 2018-12-12 14:20 +0000
                Re: Modules again David Brown <david.brown@hesbynett.no> - 2018-12-12 17:10 +0100
                Re: Modules again James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-12 13:39 -0800
                Re: Modules again scott@slp53.sl.home (Scott Lurndal) - 2018-12-12 14:19 +0000
                Re: Modules again Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2018-12-12 10:28 -0500
      Re: Big integers Ian Collins <ian-news@hotmail.com> - 2018-12-06 08:10 +1300
        Re: Big integers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-05 20:57 +0000
          Re: Big integers Ian Collins <ian-news@hotmail.com> - 2018-12-06 10:16 +1300
            Re: Big integers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-05 23:15 +0000
              Re: Big integers scott@slp53.sl.home (Scott Lurndal) - 2018-12-05 23:44 +0000
  Re: Big integers Robert Wessel <robertwessel2@yahoo.com> - 2018-12-05 02:51 -0600
  Re: Big integers antispam@math.uni.wroc.pl - 2018-12-07 15:26 +0000
    Re: Big integers Bart <bc@freeuk.com> - 2018-12-07 16:27 +0000
      Re: Big integers scott@slp53.sl.home (Scott Lurndal) - 2018-12-07 16:36 +0000
        Re: Big integers Bart <bc@freeuk.com> - 2018-12-07 17:01 +0000
      Re: Big integers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-07 17:55 +0000
      Re: Big integers antispam@math.uni.wroc.pl - 2018-12-07 19:26 +0000
        Re: Big integers Bart <bc@freeuk.com> - 2018-12-07 21:39 +0000
          Re: Big integers Ian Collins <ian-news@hotmail.com> - 2018-12-08 10:51 +1300
  Re: Big integers Anton Shepelev <anton.txt@gmail.com> - 2018-12-08 00:43 +0300
    Re: Big integers Bart <bc@freeuk.com> - 2018-12-08 01:08 +0000
    Re: Big integers David Brown <david.brown@hesbynett.no> - 2018-12-08 15:13 +0100
      Re: Big integers David Brown <david.brown@hesbynett.no> - 2018-12-08 15:15 +0100
        Re: Big integers Bart <bc@freeuk.com> - 2018-12-08 14:48 +0000
          Re: Big integers Thiago Adams <thiago.adams@gmail.com> - 2018-12-10 05:10 -0800
            Re: Big integers Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-12-10 05:22 -0800
              Re: Big integers David Brown <david.brown@hesbynett.no> - 2018-12-10 15:27 +0100
                Re: Big integers scott@slp53.sl.home (Scott Lurndal) - 2018-12-10 15:59 +0000
                Re: Big integers antispam@math.uni.wroc.pl - 2018-12-11 21:14 +0000
            Re: Big integers Bart <bc@freeuk.com> - 2018-12-10 14:56 +0000
              Re: Big integers Ike Naar <ike@iceland.freeshell.org> - 2018-12-10 17:46 +0000
                Re: Big integers Bart <bc@freeuk.com> - 2018-12-10 18:24 +0000
                Re: Big integers Thiago Adams <thiago.adams@gmail.com> - 2018-12-10 11:12 -0800
                Re: Big integers Thiago Adams <thiago.adams@gmail.com> - 2018-12-10 11:23 -0800
                Re: Big integers Bart <bc@freeuk.com> - 2018-12-10 21:44 +0000
                Re: Big integers Thiago Adams <thiago.adams@gmail.com> - 2018-12-11 10:20 -0800
                Re: Big integers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-12-11 13:15 -0800
      Re: Big integers Keith Thompson <kst-u@mib.org> - 2018-12-08 12:14 -0800
        Re: Big integers David Brown <david.brown@hesbynett.no> - 2018-12-09 13:31 +0100
      Re: Big integers "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-12-08 15:52 -0800
  Re: Big integers Bart <bc@freeuk.com> - 2018-12-16 19:29 +0000
  Re: Big integers "Tristan B. Kildaire" <deavmi@disroot.org> - 2018-12-25 12:59 +0000
    Re: Big integers Bart <bc@freeuk.com> - 2018-12-25 15:54 +0000

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