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Re: find all multiplicands and multipliers for a number

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From Dennis Lee Bieber <wlfraed@ix.netcom.com>
Subject Re: find all multiplicands and multipliers for a number
Date Sat, 11 Apr 2015 12:41:24 -0400
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On Sat, 11 Apr 2015 17:35:07 +1000, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> declaimed the following:

>On Sat, 11 Apr 2015 04:08 pm, Paul Rubin wrote:
>
>> Steven D'Aprano <steve+comp.lang.python@pearwood.info> writes:
>>> It may be a bit slow for very large numbers. On my computer, this takes
>>> 20 seconds:
>>> py> pyprimes.factors.factorise(2**111+1)
>>> [3, 3, 1777, 3331, 17539, 25781083, 107775231312019L]
>> 
>> This takes about 4 seconds on a Intel(R) Core(TM) i5-3230M CPU @ 2.60GHz
>> laptop (64 bit linux):
>
>Nice for some who have fast machines, but on my old jalopy, your code takes
>110 seconds, more than five times slower than mine. It also returns the
>wrong result:
>
>[3, 3, 3, 3, 7, 19, 73, 87211, 262657, 1.4411518807585587e+17]
>
>Oops, you have a float in there, how did that happen?
>
	Off the top of my head -- I'd suspect an older version of Python that
promoted 2**111 to a double, rather than to a Long-Int.

>>> 2**111
2596148429267413814265248164610048L

(forcing float)
>>> 2.0**111
2.596148429267414e+33
>>> 
-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

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find all multiplicands and multipliers for a number ravas <ravas@outlook.com> - 2015-04-10 16:37 -0700
  Re: find all multiplicands and multipliers for a number Dave Angel <d@davea.name> - 2015-04-10 21:16 -0400
  Re: find all multiplicands and multipliers for a number Dave Angel <davea@davea.name> - 2015-04-10 21:06 -0400
    Re: find all multiplicands and multipliers for a number Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-11 12:04 +1000
      Re: find all multiplicands and multipliers for a number Stephen Tucker <stephen_tucker@sil.org> - 2015-04-11 06:11 +0100
      Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-10 23:08 -0700
        Re: find all multiplicands and multipliers for a number Marko Rauhamaa <marko@pacujo.net> - 2015-04-11 10:14 +0300
          Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-11 09:59 -0700
            Re: find all multiplicands and multipliers for a number Marko Rauhamaa <marko@pacujo.net> - 2015-04-11 20:31 +0300
              Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-11 10:52 -0700
                Re: find all multiplicands and multipliers for a number Chris Angelico <rosuav@gmail.com> - 2015-04-12 07:10 +1000
                Re: find all multiplicands and multipliers for a number Terry Reedy <tjreedy@udel.edu> - 2015-04-11 19:58 -0400
                Re: find all multiplicands and multipliers for a number Chris Angelico <rosuav@gmail.com> - 2015-04-12 10:16 +1000
          Re: find all multiplicands and multipliers for a number wolfram.hinderer@googlemail.com - 2015-04-11 16:17 -0700
            Re: find all multiplicands and multipliers for a number Marko Rauhamaa <marko@pacujo.net> - 2015-04-12 10:17 +0300
              Primes [was Re: find all multiplicands and multipliers for a number] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-12 20:48 +1000
              Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-12 18:56 -0700
                Re: find all multiplicands and multipliers for a number Dave Angel <davea@davea.name> - 2015-04-12 22:35 -0400
                Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-12 20:30 -0700
                Re: find all multiplicands and multipliers for a number Dave Angel <davea@davea.name> - 2015-04-13 00:35 -0400
                Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-12 22:25 -0700
                Re: find all multiplicands and multipliers for a number Dave Angel <davea@davea.name> - 2015-04-13 01:43 -0400
                Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-12 22:57 -0700
                Re: find all multiplicands and multipliers for a number Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-13 17:21 +1000
                Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-13 19:42 -0700
                Re: find all multiplicands and multipliers for a number Chris Angelico <rosuav@gmail.com> - 2015-04-14 12:47 +1000
                Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-13 19:54 -0700
                Re: find all multiplicands and multipliers for a number Rustom Mody <rustompmody@gmail.com> - 2015-04-14 03:35 -0700
                Re: find all multiplicands and multipliers for a number Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-14 23:30 +1000
                Re: find all multiplicands and multipliers for a number Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-14 23:40 +1000
                Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-14 19:37 -0700
                Re: find all multiplicands and multipliers for a number Ian Kelly <ian.g.kelly@gmail.com> - 2015-04-15 09:59 -0600
                Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-15 09:21 -0700
                Re: find all multiplicands and multipliers for a number Chris Kaynor <ckaynor@zindagigames.com> - 2015-04-15 09:46 -0700
                Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-15 10:37 -0700
                Searching the archives Gil Dawson <Gil@GilDawson.com> - 2015-04-15 11:47 -0700
                Installing Python Gil Dawson <Gil@GilDawson.com> - 2015-04-15 12:09 -0700
                Re: Searching the archives Tim Golden <mail@timgolden.me.uk> - 2015-04-15 20:16 +0100
                Re: Installing Python Ned Deily <nad@acm.org> - 2015-04-15 13:32 -0700
                Re: find all multiplicands and multipliers for a number Rustom Mody <rustompmody@gmail.com> - 2015-04-15 21:17 -0700
        Re: find all multiplicands and multipliers for a number Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-11 17:35 +1000
          Re: find all multiplicands and multipliers for a number jonas.thornvall@gmail.com - 2015-04-11 01:47 -0700
          Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-11 09:31 -0700
            Re: find all multiplicands and multipliers for a number Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-12 12:22 +1000
              Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-11 21:24 -0700
                Re: find all multiplicands and multipliers for a number Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-12 14:29 +1000
          Re: find all multiplicands and multipliers for a number Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-04-11 12:41 -0400
            Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-11 10:02 -0700
        Re: find all multiplicands and multipliers for a number Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-04-11 12:37 -0400
      Re: find all multiplicands and multipliers for a number Brian Gladman <blindanagram@nowhere.net> - 2015-04-12 10:34 +0100
        Re: find all multiplicands and multipliers for a number Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-13 00:29 +1000
          Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-12 10:20 -0700
            Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-12 10:23 -0700
            Re: find all multiplicands and multipliers for a number Brian Gladman <blindanagram@nowhere.net> - 2015-04-12 20:15 +0100
              Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-12 12:45 -0700
          Re: find all multiplicands and multipliers for a number Brian Gladman <blindanagram@nowhere.net> - 2015-04-12 20:07 +0100
  Re: find all multiplicands and multipliers for a number Paul Rubin <no.email@nospam.invalid> - 2015-04-10 18:28 -0700
  Re: find all multiplicands and multipliers for a number Dave Farrance <DaveFarrance@OMiTTHiSyahooANDTHiS.co.uk> - 2015-04-11 10:03 +0100
  Re: find all multiplicands and multipliers for a number ravas <ravas@outlook.com> - 2015-04-11 10:11 -0700

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