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Search: Posts Made By: paulunderwood
Forum: Hardware 2020-08-08, 23:07
Replies: 1
Views: 53
Posted By paulunderwood
w00t not free but dead cheap

AMD 1090T w/ Original heatsink on ASUS board with 4GB RAM. Have two. £15 each. Pickup only from Gloucestershire, England.

Job lot of:-
4x G34 6174 12 core (untested)
4x G34 6176 12 core...
Forum: Software 2020-08-08, 15:36
Replies: 581
Views: 73,763
Posted By paulunderwood
see:...

see: https://mersenneforum.org/showpost.php?p=552855&postcount=177

Does it interest you?
Forum: And now for something completely different 2020-08-08, 00:06
Replies: 13
Views: 2,719
Posted By paulunderwood
Go to https://primes.utm.edu/bios/ and create a...

Go to https://primes.utm.edu/bios/ and create a new prover account based on a "c" code for Primo if you don't already have one. Then you can submit your newly certified prime under the new code with...
Forum: PARI/GP 2020-08-06, 05:28
Replies: 272
Views: 11,949
Posted By paulunderwood
cat test.gp V=read("./myvec.txt"); ...

cat test.gp
V=read("./myvec.txt");
for(v=1,#V,print(V[v]))


echo "[1,2,3,4]" > myvec.txt; gp -q < test.gp
1
2
3
4
Forum: PARI/GP 2020-08-06, 04:45
Replies: 272
Views: 11,949
Posted By paulunderwood
https://rosettacode.org/wiki/Parse_command-line_ar...

https://rosettacode.org/wiki/Parse_command-line_arguments#PARI.2FGP

"GP exists in a REPL (https://en.wikipedia.org/wiki/Read%E2%80%93eval%E2%80%93print_loop) and so it doesn't make sense to parse...
Forum: GpuOwl 2020-08-06, 01:11
Replies: 2,393
Views: 135,007
Posted By paulunderwood
https://www.thefreedictionary.com/cofactor ...

https://www.thefreedictionary.com/cofactor

"1. One of two or more contributing factors."

:grin:
Forum: GpuOwl 2020-08-05, 23:42
Replies: 2,393
Views: 135,007
Posted By paulunderwood
It looks like the cofactor is given:...

It looks like the cofactor is given: 765044109502655639249
Forum: Math 2020-08-05, 15:06
Replies: 6
Views: 192
Posted By paulunderwood
Yes. Addition and subtraction and mod 2^p-1 does...

Yes. Addition and subtraction and mod 2^p-1 does not require FFT.
Forum: Software 2020-08-05, 14:50
Replies: 9
Views: 232
Posted By paulunderwood
Prime95/mprime is Intel/AMD X86/64 only. For ARM...

Prime95/mprime is Intel/AMD X86/64 only. For ARM you need to run mlucas (https://www.mersenneforum.org/mayer/README.html).

Basically:

Download the asimd image. bunzip it.
tune.
communicate...
Forum: Math 2020-08-05, 13:30
Replies: 6
Views: 192
Posted By paulunderwood
You need a data structure to hold the numbers....

You need a data structure to hold the numbers. The simplest would be a one dimensional array (https://en.wikipedia.org/wiki/Array_data_structure#One-dimensional_arrays) and a byte or two indicating...
Forum: Miscellaneous Math 2020-08-03, 19:36
Replies: 75
Views: 5,805
Posted By paulunderwood
Thumbs down House of cards

[n,b] = [79786523, 2982537] is a counterexample to the test given in post #74 where r=1. This was overlooked because of the same programming error indicated in post #75. The only thing to be lifted...
Forum: Miscellaneous Math 2020-08-03, 14:20
Replies: 75
Views: 5,805
Posted By paulunderwood
w00t 1+1 selfridges

Here is a 1+1 selfridges algorithm:

Given a non-square n find b:


kronecker(b,n)==1
kronecker(1-b,n)==-1
gcd(4-b,n)==1
gcd(4-2*b,n)==1
Forum: Miscellaneous Math 2020-08-02, 09:15
Replies: 75
Views: 5,805
Posted By paulunderwood
Cool Second draft

:book: :mooc:
Forum: Proth Prime Search 2020-07-31, 22:23
Replies: 158
Views: 35,465
Posted By paulunderwood
Congratulations for a top 20 prime!

Congratulations for a top 20 prime!
Forum: Programming 2020-07-31, 11:03
Replies: 53
Views: 8,195
Posted By paulunderwood
Arrow Here is a gwnum program that tests...

Here is a gwnum program that tests Euler+Frobenius as per https://mersenneforum.org/showpost.php?p=552286&postcount=74. :fish1:

power_quadratic.c tests over x^2-2*x-2^s which arguably safer than...
Forum: PARI/GP 2020-07-30, 13:56
Replies: 12
Views: 410
Posted By paulunderwood
?solve solve(X=a,b,expr): real root of...

?solve
solve(X=a,b,expr): real root of expression expr (X between a and b), where
expr(a)*expr(b)<=0.


For logarithmic equations use pen and paper and an internet search engine.
Forum: Miscellaneous Math 2020-07-30, 01:10
Replies: 75
Views: 5,805
Posted By paulunderwood
Red face Answer and warning

Apart form the ill-formed question, writing b=s^2 (and found by trial and error) the answer is:

(x*(1-s^2))^((n+1)/2) == s*(1-s^2)*kronecker(2*(1-s),n) (mod n, x^2-2*x+s^2),

Warning: this...
Forum: Linux 2020-07-29, 04:04
Replies: 13
Views: 510
Posted By paulunderwood
This looks like a problem with unattended...

This looks like a problem with unattended upgrades. Remove it (https://ostechnix.com/how-to-disable-unattended-upgrades-on-ubuntu/) with sudo apt remove unattended-upgrades or disable it via sudo...
Forum: Linux 2020-07-29, 03:31
Replies: 13
Views: 510
Posted By paulunderwood
This...

This (https://serverfault.com/questions/884597/how-to-find-reason-for-system-reboot-or-shutdown-in-ubuntu-16-04-system) says run the command egrep -ir "(shut|reboot)" /var/log/*
Forum: Linux 2020-07-29, 02:58
Replies: 13
Views: 510
Posted By paulunderwood
Freshly installed Debian has to be coaxed into...

Freshly installed Debian has to be coaxed into not suspending (https://wiki.debian.org/Suspend#Disable_suspend_and_hibernation) etc after ~20 minutes with a mask command. I wonder if your problem is...
Forum: Miscellaneous Math 2020-07-28, 18:53
Replies: 75
Views: 5,805
Posted By paulunderwood
Question Simplification

Recap: The solutions to x^2-2^r*x+b=0 are x=2^(r-1)+-sqrt(4^(r-1)-b).

Let r=1. Then the solutions are to the equation x^2-2*x+b=0 which are x=1+-sqrt(1-b)

We have to have kronecker(1-b,n)==-1,...
Forum: Miscellaneous Math 2020-07-28, 02:05
Replies: 75
Views: 5,805
Posted By paulunderwood
Forum: Miscellaneous Math 2020-07-27, 14:23
Replies: 75
Views: 5,805
Posted By paulunderwood
Cool most general test (revised)

I found some counterexamples to the above.

The revised test:


b%n!=0
!issquare(n)
gcd(a^2-b,n)==1
gcd(a^2-2*b,n)==1
gcd(a^2-3*a,n)==1
Forum: Miscellaneous Math 2020-07-27, 11:51
Replies: 75
Views: 5,805
Posted By paulunderwood
To fool 2-PSPs and Carmichael numbers lists...

To fool 2-PSPs and Carmichael numbers lists gcd(a^2-3*b,n)==1 is also required. :cool:
Forum: Miscellaneous Math 2020-07-27, 10:15
Replies: 75
Views: 5,805
Posted By paulunderwood
most general test

Let x^2-a*x+b=0. The solutions are x=a/2 +- sqrt(a^2-4*b)/2.

The test is:


b%n!=0
!issquare(n)
gcd(a^2-b,n)==1
gcd(a^2-2*b,n)==1
kronecker(a^2-4*b,n)==-1
Showing results 1 to 25 of 1000

 
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