##### How do I code this equation in python (factor ceiling(2^127-1))
 How do I code this equation in python (factor ceiling(2^127-1)) Pleiades Not Blown Up Yet Posts: 58 Threads: 19 Joined: Apr 2018 Reputation: Apr-21-2018, 08:38 PM I want to factor this equation and I was doing so well on wolfram but now they want me to pay to see answers. Bummer! How do I write the code for this one? Any help is Awesome! Factor ceiling(2^127-1)-1 http://www.wolframalpha.com/widgets/view...ddee57d91e Reply Skaperen Black Knight Posts: 3,994 Threads: 1,300 Joined: Sep 2016 Reputation: Apr-22-2018, 05:15 AM (This post was last modified: Apr-22-2018, 05:26 AM by Skaperen.) how do you write ceiling(2^127-1)-1? i can understand (2^127-1)-1 but i don't understand ceiling() in the context of factoring. ceiling(170141183460469231731687303715884105727)-1? are you trying to compile a list of Mersenne Primes? Tradition is peer pressure from dead people What do you call someone who speaks three languages? Trilingual. Two languages? Bilingual. One language? American. Reply Posts: 3,291 Threads: 45 Joined: Jan 2018 Reputation: Apr-22-2018, 05:57 AM cypari gives some result: ```>>> import cypari >>> cypari.pari('factor({})'.format(2**127-2)) [2, 1; 3, 3; 7, 2; 19, 1; 43, 1; 73, 1; 127, 1; 337, 1; 5419, 1; 92737, 1; 649657, 1; 77158673929, 1]``` Reply Pleiades Not Blown Up Yet Posts: 58 Threads: 19 Joined: Apr 2018 Reputation: Apr-22-2018, 07:39 AM (This post was last modified: Apr-22-2018, 07:39 AM by Pleiades.) (Apr-22-2018, 05:15 AM)Skaperen Wrote: how do you write ceiling(2^127-1)-1? i can understand (2^127-1)-1 but i don't understand ceiling() in the context of factoring. ceiling(170141183460469231731687303715884105727)-1? are you trying to compile a list of Mersenne Primes? Skaperen I'm trying to predict Mersenne Primes and I know that is nuts, but I have spare time so what the heck lol. (Apr-22-2018, 05:57 AM)Gribouillis Wrote: cypari gives some result: ` >>> import cypari >>> cypari.pari('factor({})'.format(2**127-2)) [2, 1; 3, 3; 7, 2; 19, 1; 43, 1; 73, 1; 127, 1; 337, 1; 5419, 1; 92737, 1; 649657, 1; 77158673929, 1] `Hi, I'm now trying to do this calculation at the interpreter and I get this error. Maybe in 10 years I'll see the answer to this one. No bad on you, but this is very complex. My computer is running the latest version of mpmath 1.0.0 ERROR_ 3**1279 % 19.1 OverflowError: int too large to convert to float Reply Posts: 3,291 Threads: 45 Joined: Jan 2018 Reputation: Apr-22-2018, 08:17 AM (This post was last modified: Apr-22-2018, 08:19 AM by Gribouillis.) (Apr-22-2018, 07:39 AM)Pleiades Wrote: OverflowError: int too large to convert to floatYou need the floating type `mpmath.mpf`. The following computation may be correct (read the doc!) ```>>> import mpmath as mp >>> mp.mp.dps = 1000 >>> mp.mp.prec 3325 >>> x = mp.mpf(3**1279) >>> x mpf('17301541007910038054176056432452867095149043770336183739760994896914962855011729112692135469308113595623662446442598795834444897233706143344824357701420610156423345105638078275879693218333055393875886226458620734496461814517152992352402982745998689203987491576943864064210130929012975963553401138869026447532834194444684876122440822192338479455455335994013248316240321358466758500551665434276274478532775337486153362645579799959393898179890245190220628605618273528084601403702463029225950540686613177600948606835157545386013111476205803857649578582946755008105822347197520438156375214337925994262260644194653867.0') >>> x % mp.mpf('19.1') mpf('10.19999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999986211221154848220654005392902057139770156790286166144188800371401237452170538589543598035521683264914310586337686699894347939024860146540757548385574874504630831265632890197664535441563639513497048756683543708442778829491602757769872393215591581152938167421054163471394836743703044131001404204016205461841021455948652709053963994607698563023642172696945794949806477041895118333497516253529717948650209753919929653496184540071834200082524982267781226809556415809041082332587896492941756602172886446388115227194726605314781134096334203545572724145359345153758473917409997845778716764066425820393664286016039105526')```You can do it without mpmath, using only integers:```>>> (3**1279*10) % 191 102``` Reply Skaperen Black Knight Posts: 3,994 Threads: 1,300 Joined: Sep 2016 Reputation: Apr-23-2018, 03:01 AM what is it you are trying to accomplish in your spare time ... factorize all non-prime Mersenne numbers? or factorize the numbers one less than Mersenne numbers? or find which are prime? are you using a gauntlet of multi-core cloud instances? Tradition is peer pressure from dead people What do you call someone who speaks three languages? Trilingual. Two languages? Bilingual. One language? American. Reply

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