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 Showing results 1 to 25 of 1000 Search took 0.24 seconds. Search: Posts Made By: R. Gerbicz
 2022-05-15, 17:13 Replies: 82 Views: 3,318 Posted By R. Gerbicz Yeah. One very "trivial" improvement would come... Yeah. One very "trivial" improvement would come to call a faster prp routine, so not call the gmp's built-in mpz_probab_prime_p function. Maybe use pfgw, or directly using the gw library. Notice that...
 Forum: Factoring 2022-04-20, 23:46 Replies: 27 Views: 1,208 Posted By R. Gerbicz False, another way is to show a 1
 Forum: Puzzles 2022-04-17, 20:33 Replies: 3 Views: 595 Posted By R. Gerbicz All non-negative integers are reachable! ... All non-negative integers are reachable! consider the following 9 ways of reductions, the first number is always the starter, then we show each following numbers in the routine: 8*N+1 -> 24*N+3 ->...
 Forum: Dobri 2022-04-11, 15:47 Replies: 16 Views: 1,149 Posted By R. Gerbicz On quantum computer we already have the... On quantum computer we already have the polynomial time factorization Shor's algorithm. I'd say it is quite unlikely that the quad binary approach would be in polynomial time using quantum [because...
 Forum: Dobri 2022-04-11, 15:09 Replies: 16 Views: 1,149 Posted By R. Gerbicz And of course this is not a simplification of the... And of course this is not a simplification of the problem, because it is a quadratic optimization problem using binary integers. And I'd prefer this (known) form: min{0 : x*y=n, x>=2, y>=2, x and...
 Forum: Miscellaneous Math 2022-04-10, 22:37 Replies: 14 Views: 940 Posted By R. Gerbicz Recommending 6 (six) more problems what you could... Recommending 6 (six) more problems what you could easily attack: https://en.wikipedia.org/wiki/Millennium_Prize_Problems all of them worth 1 million bucks (USD).
 Forum: GMP-ECM 2022-04-01, 16:17 Replies: 24 Views: 1,786 Posted By R. Gerbicz I've needed also: sudo apt-get install... I've needed also: sudo apt-get install libtool
 Forum: Lounge 2022-03-15, 18:58 Replies: 169 Views: 32,530 Posted By R. Gerbicz Recent video about William Shanks, who hold the... Recent video about William Shanks, who hold the record computation of pi for almost a century: https://www.youtube.com/watch?v=DmfxIhmGPP4 And a follow up video to find the first 100 digits of pi by...
 Forum: Puzzles 2022-02-23, 15:17 Replies: 13 Views: 1,267 Posted By R. Gerbicz Yes, you're right. Yes, you're right.
 Forum: Puzzles 2022-02-22, 16:09 Replies: 13 Views: 1,267 Posted By R. Gerbicz That is a very nice puzzle, complete solution... That is a very nice puzzle, complete solution (with little maths): Work mod 5, since there are 5 different things that Penn and Teller can choose, say they have chosen x on the left and y on the...
 Forum: Puzzles 2022-02-21, 12:41 Replies: 14 Views: 1,139 Posted By R. Gerbicz Hm, it is even faster: static inline bool... Hm, it is even faster: static inline bool issquare(uint64_t x) { uint64_t sqr = 0.5+sqrt(x); return sqr * sqr == x; } and gives correct answer for the full [0,2^64) range (for the same...
 Forum: Puzzles 2022-02-20, 21:13 Replies: 14 Views: 1,139 Posted By R. Gerbicz It is easier: uint64_t sqr = sqrtl(x); return... It is easier: uint64_t sqr = sqrtl(x); return sqr * sqr == x; if you call it for 64 bits number, so 0<=x<2^64, then 0<=sqr<2^32, so it couldn't report a nonsquare number as a square, because in...
 Forum: Puzzles 2022-02-20, 20:57 Replies: 14 Views: 1,139 Posted By R. Gerbicz Using one core that is true, and it is almost... Using one core that is true, and it is almost true for many cores/threads, because we're testing res values in increasing order, just check a%M values. Good question, but it seems that the...
 Forum: Puzzles 2022-02-20, 17:50 Replies: 14 Views: 1,139 Posted By R. Gerbicz OK, but testing smaller trivial ranges is also... OK, but testing smaller trivial ranges is also not that bad, because those contain many solutions so it is easier and quicker to find a problem, when observed that the code needs 64|M I've justed...
 Forum: Puzzles 2022-02-19, 22:35 Replies: 14 Views: 1,139 Posted By R. Gerbicz OK, (almost) completely new approach. Using... OK, (almost) completely new approach. Using M=100800 with t=8 threads done a=1..8000000, found 126 solutions in 1627 sec. Roughly seven times faster what could be your code, and 20 or so times...
 Forum: Puzzles 2022-02-18, 22:12 Replies: 14 Views: 1,139 Posted By R. Gerbicz Replace the worker with the following: void... Replace the worker with the following: void *worker(void *data) { uint64_t a; uint64_t b; uint64_t c; (void)data;
 Forum: MattcAnderson 2022-02-15, 22:31 Replies: 15 Views: 410 Posted By R. Gerbicz For Mathematica: "PrimeQ first tests for... For Mathematica: "PrimeQ first tests for divisibility using small primes, then uses the Miller–Rabin strong pseudoprime test base 2 and base 3, and then uses a Lucas test." ref....
 Forum: MattcAnderson 2022-02-15, 17:51 Replies: 15 Views: 410 Posted By R. Gerbicz On the given link: "It returns false if n is... On the given link: "It returns false if n is shown to be composite within one strong pseudo-primality test and one Lucas test. It returns true otherwise." Likely they are doing some trial...
 2022-02-13, 21:37 Replies: 26 Views: 2,028 Posted By R. Gerbicz There is an easy heuristic why there could be no... There is an easy heuristic why there could be no more Motzkin primes: if n is in the [3^k,3^(k+1)) interval then there are only O(2^k) M[n] Motzkin numbers that is coprime to 3. Trivially...
 Forum: Miscellaneous Math 2022-02-13, 12:43 Replies: 9 Views: 957 Posted By R. Gerbicz Do you know that for a=777 it is giving... Do you know that for a=777 it is giving palindrome number only if n=4 ? (Generalize it for any "a" number) Inspect the numbers: (13:38) gp > f(n)=10^n+777*10^(n-3)+1 %3 = (n)->10^n+777*10^(n-3)+1...
 2022-02-11, 23:34 Replies: 26 Views: 2,028 Posted By R. Gerbicz Definitely not new result, found:... Definitely not new result, found: https://arxiv.org/abs/1703.00826 , see table 1, only ~4 years old. But we could still write down these other proofs, at least to arxiv.org . Rob's automata approach...
 2022-02-09, 17:00 Replies: 26 Views: 2,028 Posted By R. Gerbicz For any odd p prime: T1:... For any odd p prime: T1: M(p-2)==(-1+kronecker(p,3))/2 mod p T2: M(2*p-1)==3*(1+kronecker(p,3))/2 mod p (it is also true for p=2, but you have to do the division "before" mod; p=3 could be also...
 2022-02-08, 20:51 Replies: 26 Views: 2,028 Posted By R. Gerbicz Using an equivalent form for Motzkin: ... Using an equivalent form for Motzkin: M(n)=sum(k=0,n\2,binomial(n,2*k)*C(k))=sum(k=0,n\2,1/(k+1)*n!/((n-2*k)!*k!^2)), here the k-th term for n=p-2:...
 2022-02-08, 19:29 Replies: 26 Views: 2,028 Posted By R. Gerbicz That is really interesting, to extend it: if... That is really interesting, to extend it: if p%6==5 then Motzkin(2*p-1) is divisible by p.
 Forum: Lounge 2022-02-03, 21:56 Replies: 112 Views: 5,346 Posted By R. Gerbicz I was close to the optimal, what is 3.4212, and... I was close to the optimal, what is 3.4212, and proved by Alex Selby: http://sonorouschocolate.com/notes/index.php?title=The_best_strategies_for_Wordle (he solved the famous Eternity puzzle) If...
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