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One comment from @Fast-Nop made me remember something I had promised myself not to. Specifically the USB thing.
So there I was, Lieutenant Jr at a warship (not the one my previous rants refer to), my main duties as navigation officer, and secondary (and unofficial) tech support and all-around "computer guy".
Those of you who don't know what horrors this demonic brand pertains to, I envy you. But I digress. In the ship, we had Ethernet cabling and switches, but no DHCP, no server, not a thing. My proposition was shot down by the CO within 2 minutes. Yet, we had a curious "network". As my fellow... colleagues had invented, we had something akin to token ring, but instead of tokens, we had low-rank personnel running around with USB sticks, and as for "rings", well, anyone could snatch up a USB-carrier and load his data and instructions to the "token". What on earth could go wrong with that system?
What indeed.
We got 1 USB infected with a malware from a nearby ship - I still don't know how. Said malware did the following observable actions(yes, I did some malware analysis - As I said before, I am not paid enough):
- Move the contents on any writeable media to a folder with empty (or space) name on that medium. Windows didn't show that folder, so it became "invisible" - linux/mac showed it just fine
- It created a shortcut on the root folder of said medium, right to the malware. Executing the shortcut executed the malware and opened a new window with the "hidden" folder.
Childishly simple, right? If only you knew. If only you knew the horrors, the loss of faith in humanity (which is really bad when you have access to munitions, explosives and heavy weaponry).
People executed the malware ON PURPOSE. Some actually DISABLED their AV to "access their files". I ran amok for an entire WEEK to try to keep this contained. But... I underestimated the USB-token-ring-whatever protocol's speed and the strength of a user's stupidity. PCs that I cleaned got infected AGAIN within HOURS.
I had to address the CO to order total shutdown, USB and PC turnover to me. I spent the most fun weekend cleaning 20-30 PCs and 9 USBs. What fun!
What fun, morons. Now I'll have nightmares of those days again.9 -
Funniest meeting ever!
Some years ago, there was the regular department meeting where useless news from upper management were handed down. The team I was in was also there: team lead, co-worker and me. The team lead had a new girl and was daydreaming of their nights, my co-worker wasn't quite back from the football match on the weekend, and I was playing chess on my mobile.
Department lead was blah blah blah and when can we do this on your rig? We looked at each other and instantly realised that none had been paying attention.
My co-worker was the fastest to recover and straight-facedly turned to me: "Well Fast-Nop, that's your domain."
I picked the ball up before team lead could say something: "Sure, but schedule appointment is for our lead."
Our lead couldn't contradict us and then had to negotiate a schedule while trying to find out what it was about. *LOL*2 -
Two big moments today:
1. Holy hell, how did I ever get on without a proper debugger? Was debugging some old code by eye (following along and keeping track mentally, of what the variables should be and what each step did). That didn't work because the code isn't intuitive. Tried the print() method, old reliable as it were. Kinda worked but didn't give me enough fine-grain control.
Bit the bullet and installed Wing IDE for python. And bam, it hit me. How did I ever live without step-through, and breakpoints before now?
2. Remember that non-sieve prime generator I wrote a while back? (well maybe some of you do). The one that generated quasi lucas carmichael (QLC) numbers? Well thats what I managed to debug. I figured out why it wasn't working. Last time I released it, I included two core methods, genprimes() and nextPrime(). The first generates a list of primes accurately, up to some n, and only needs a small handful of QLC numbers filtered out after the fact (because the set of primes generated and the set of QLC numbers overlap. Well I think they call it an embedding, as in QLC is included in the series generated by genprimes, but not the converse, but I digress).
nextPrime() was supposed to take any arbitrary n above zero, and accurately return the nearest prime number above the argument. But for some reason when it started, it would return 2,3,5,6...but genprimes() would work fine for some reason.
So genprimes loops over an index, i, and tests it for primality. It begins by entering the loop, and doing "result = gffi(i)".
This calls into something a function that runs four tests on the argument passed to it. I won't go into detail here about what those are because I don't even remember how I came up with them (I'll make a separate post when the code is fully fixed).
If the number fails any of these tests then gffi would just return the value of i that was passed to it, unaltered. Otherwise, if it did pass all of them, it would return i+1.
And once back in genPrimes() we would check if the variable 'result' was greater than the loop index. And if it was, then it was either prime (comparatively plentiful) or a QLC number (comparatively rare)--these two types and no others.
nextPrime() was only taking n, and didn't have this index to compare to, so the prior steps in genprimes were acting as a filter that nextPrime() didn't have, while internally gffi() was returning not only primes, and QLCs, but also plenty of composite numbers.
Now *why* that last step in genPrimes() was filtering out all the composites, idk.
But now that I understand whats going on I can fix it and hypothetically it should be possible to enter a positive n of any size, and without additional primality checks (such as is done with sieves, where you have to check off multiples of n), get the nearest prime numbers. Of course I'm not familiar enough with prime number generation to know if thats an achievement or worthwhile mentioning, so if anyone *is* familiar, and how something like that holds up compared to other linear generators (O(n)?), I'd be interested to hear about it.
I also am working on filtering out the intersection of the sets (QLC numbers), which I'm pretty sure I figured out how to incorporate into the prime generator itself.
I also think it may be possible to generator primes even faster, using the carmichael numbers or related set--or even derive a function that maps one set of upper-and-lower bounds around a semiprime, and map those same bounds to carmichael numbers that act as the upper and lower bound numbers on the factors of a semiprime.
Meanwhile I'm also looking into testing the prime generator on a larger set of numbers (to make sure it doesn't fail at large values of n) and so I'm looking for more computing power if anyone has it on hand, or is willing to test it at sufficiently large bit lengths (512, 1024, etc).
Lastly, the earlier work I posted (linked below), I realized could be applied with ECM to greatly reduce the smallest factor of a large number.
If ECM, being one of the best methods available, only handles 50-60 digit numbers, & your factors are 70+ digits, then being able to transform your semiprime product into another product tree thats non-semiprime, with factors that ARE in range of ECM, and which *does* contain either of the original factors, means products that *were not* formally factorable by ECM, *could* be now.
That wouldn't have been possible though withput enormous help from many others such as hitko who took the time to explain the solution was a form of modular exponentiation, Fast-Nop who contributed on other threads, Voxera who did as well, and support from Scor in particular, and many others.
Thank you all. And more to come.
Links mentioned (because DR wouldn't accept them as they were):
https://pastebin.com/MWechZj912 -
@Fast-Nop This one's for you, buddy. Took me all freaking day to figure out how to avoid unsafe-inline when registering a service worker. XD
7 -
Tried to reply to @Fast-Nop who had replied to someone wondering if C would be a good first language.
IMHO C should have been put to sleep ages ago. A few years ago I downloaded the latest, greatest C Standard. For a language billed as small and simple (by many) it was over 800 pages long. Still there's a lot that's unspecified like order of evaluation of function arguments. Int etc is implementation dependent. And error handling, let's not go there. The macro assembler throws away all the semantics leaving behind a cryptic value. It's a complex language due to the innumerable interactions possible.
It's been called assembly language for the PDP-11 minicomputer. Recently learned that even the VAX-1 was built from SSI chips like the 4-bit 74181 ALU. The VAX.
Anyway I had several excellent books on programming style written by Henry Ledgard. He despaired of making C look readable. I commend his books which are so old that the code is UPPERCASE A lot of he wrote had to do with program design, naming things, writing good comments and that the visual shape of a program assists mental clarity.23 -
This one is for @Fast-Nop
Both a rant and a joke/meme.
Its also funny because its true. Couple of teams (team responsible for orders and team responsible for accounting) are in seclusion in a meeting room right now cleaning up the web team's screw up.
5 -
Heya @Fast-Nop
Here's to your many sevens (7).
Beautiful assembly, perfect with that leading three (3).
Cheers mate
5 -
i pack my developers' weapon box and take with me:
-- sting, a sword the size of a butter knife --
- awesome for cutting pizza
- +3 luck (while equipped, bug encounters are increased x3)
- it glows blueish when PMs are nearby.
(probs to @Fast-Nop :-)
what do you equip?10 -
After learning a bit about alife I was able to write
another one. It took some false starts
to understand the problem, but afterward I was able to refactor the problem into a sort of alife that measured and carefully tweaked various variables in the simulator, as the algorithm
explored the paramater space. After a few hours of letting the thing run, it successfully returned a remainder of zero on 41.4% of semiprimes tested.
This is the bad boy right here:
tracks[14]
[15, 2731, 52, 144, 41.4]
As they say, "he ain't there yet, but he got the spirit."
A 'track' here is just a collection of critical values and a fitness score that was found given a few million runs. These variables are used as input to a factoring algorithm, attempting to factor
any number you give it. These parameters tune or configure the algorithm to try slightly different things. After some trial runs, the results are stored in the last entry in the list, and the whole process is repeated with slightly different numbers, ones that have been modified
and mutated so we can explore the space of possible parameters.
Naturally this is a bit of a hodgepodge, but the critical thing is that for each configuration of numbers representing a track (and its results), I chose the lowest fitness of three runs.
Meaning hypothetically theres room for improvement with a tweak of the core algorithm, or even modifications or mutations to the
track variables. I have no clue if this scales up to very large semiprime products, so that would be one of the next steps to test.
Fitness also doesn't account for return speed. Some of these may have a lower overall fitness, but might in fact have a lower basis
(the value of 'i' that needs to be found in order for the algorithm to return rem%a == 0) for correctly factoring a semiprime.
The key thing here is that because all the entries generated here are dependent on in an outer loop that specifies [i] must never be greater than a/4 (for whatever the lowest factor generated in this run is), we can potentially push down the value of i further with some modification.
The entire exercise took 2.1735 billion iterations (3-4 hours, wasn't paying attention) to find this particular configuration of variables for the current algorithm, but as before, I suspect I can probably push the fitness value (percentage of semiprimes covered) higher, either with a few
additional parameters, or a modification of the algorithm itself (with a necessary rerun to find another track of equivalent or greater fitness).
I'm starting to bump up to the limit of my resources, I keep hitting the ceiling in my RAD-style write->test->repeat development loop.
I'm primarily using the limited number of identities I know, my gut intuition, combine with looking at the numbers themselves, to deduce relationships as I improve these and other algorithms, instead of relying strictly on memorizing identities like most mathematicians do.
I'm thinking if I want to keep that rapid write->eval loop I'm gonna have to upgrade, or go to a server environment to keep things snappy.
I did find that "jiggling" the parameters after each trial helped to explore the parameter
space better, so I wrote some methods to do just that. But what I wouldn't mind doing
is taking this a bit of a step further, and writing some code to optimize the variables
of the jiggle method itself, by automating the observation of real-time track fitness,
and discarding those changes that lead to the system tending to find tracks with lower fitness.
I'd also like to break up the entire regime into a training vs test set, but for now
the results are pretty promising.
I knew if I kept researching I'd likely find extensions like this. Of course tested on
billions of semiprimes, instead of simply millions, or tested on very large semiprimes, the
effect might disappear, though the more i've tested, and the larger the numbers I've given it,
the more the effect has become prevalent.
Hitko suggested in the earlier thread, based on a simplification, that the original algorithm
was a tautology, but something told me for a change that I got one correct. Without that initial challenge I might have chalked this up to another false start instead of pushing through and making further breakthroughs.
I'd also like to thank all those who followed along, helped, or cheered on the madness:
In no particular order ,demolishun, scor, root, iiii, karlisk, netikras, fast-nop, hazarth, chonky-quiche, Midnight-shcode, nanobot, c0d4, jilano, kescherrant, electrineer, nomad,
vintprox, sariel, lensflare, jeeper.
The original write up for the ideas behind the concept can be found at:
https://devrant.com/rants/7650612/...
If I left your name out, you better speak up, theres only so many invitations to the orgy.
Firecode already says we're past max capacity!5 -
I've been kinda missing linux lately so I've been thinking about dual booting it on my desktop,
And considering I've only mainly used RPM based distros(Mainly RedHat Linux and later Fedora almost exclusively)
I've thought about getting out of my "RPM zone of comfort" and distro hopping for like a year between different other systems and seeing what else is there and how it compares to Fedora.
Any suggestions and what I should try?
I thought I'd start easy and take Baboontu (Ubuntu), mostly because I'm planning on making a Minecraft Bedrock server for friends in the near future which apparently is only available for on Ubuntu so I want to get used to it.
Currently the distros I wanted to try are:
Ubuntu -> Linux Mint(With how much @Fast-Nop has been praising it how can I not try it) -> Arch(Because I wanna see what all the fuss is about) -> Gentoo Linux -> Slackware(Because I recently learned that this thing still actually exists and is still active and gets updated, so wanted to see this Legendary distro)
Any others y'all can recommend?
I'm planning to try and use each distro at least for a month and try to only use Linux, only switching to Windows if there is *no* way to do it in the distro.2 -
New year, new Google HashCode!!!
I need a new stupid name for my team, last year "SicroMoft" by @Fast-Nop was great, but this time I need something even better (or worse)
Also, who else is participating?6
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