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| Date | Fri, 10 Apr 2015 21:06:15 -0400 |
| From | Dave Angel <davea@davea.name> |
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| Subject | Re: find all multiplicands and multipliers for a number |
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Show key headers only | View raw
On 04/10/2015 07:37 PM, ravas wrote: > def m_and_m(dividend): > rlist = [] > dm = divmod > end = (dividend // 2) + 1 > for divisor in range(1, end): > q, r = dm(dividend, divisor) > if r is 0: > rlist.append((divisor, q)) > return rlist > > print(m_and_m(999)) > --- > output: [(1, 999), (3, 333), (9, 111), (27, 37), (37, 27), (111, 9), (333, 3)] > --- > > How do we describe this function? > Does it have an established name? > What would you call it? > Does 'Rosetta Code' have it or something that uses it? > Can it be written to be more efficient? > What is the most efficient way to exclude the superfluous inverse tuples? > Can it be written for decimal numbers as input and/or output? > > Thank you! > I'd call those factors of the original number. For completeness, I'd include (999,1) at the end. If it were my problem, I'd be looking for only prime factors. Then if someone wanted all the factors, they could derive them from the primes, by multiplying all possible combinations. The program can be sped up most obviously by stopping as soon as you get a tuple where divisor > q. At that point, you can just repeat all the items, reversing divisor and q for each item. Of course, now I notice you want to eliminate them. So just break out of the loop when divisor > q. You can gain some more speed by calculating the square root of the dividend, and stopping when you get there. But the real place to get improvement is to only divide by primes, rather than every possible integer. And once you've done the division, let q be the next value for dividend. So you'll get a list like [3, 3, 3, 37] for the value 999 See: http://rosettacode.org/wiki/Factors_of_an_integer#Python -- DaveA
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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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