wbhart

53 ms·

451.
by wbhart 15y ago
It's still an issue for me. I'm using the IP addresses for now. They say on their blog that this is likely propagation issues though.... and it's back.
452.
by wbhart 15y ago
From the article, "By definition, plagiarism only happens when credit to sources is not given, which was never the case with Rybka." I simply do not agree with this. I cannot copy slabs of open source code, incorporate them into my product
453.
FFT bignum multiplication (github.com)
6 points by wbhart 15y ago|0 comments
454.
by wbhart 15y ago
One of the examples in the repository is an implementation of malloc. I tend to think of Go as an attempt to redefine what a systems programming language is (hence the "modern"). I don't think that there can be an established definition of
455.
by wbhart 15y ago
It's great to see a language which doesn't ignore 20th and 21st century programming language theory. It's tremendously boring waiting for the future to happen.... Anyhow, the type system looks quite interesting. The choice of LLVM for C int
456.
by wbhart 15y ago
The NSA recently stated that they are only a couple of years ahead. And by that I take it they mean their computers are bigger. Recall that they are a military outfit. Only a small part of what they do is crypto related. Despite them having
457.
by wbhart 15y ago
Kida wrote UBASIC I believe.
458.
by wbhart 15y ago
Perhaps they are tables of precomputed inverses of primes to speed up the trial division. There might be up to 100000 entries in the file if this is the case. I can't think what else would be in the file. I would have guessed the file was g
459.
by wbhart 15y ago
The mpqs code actually compiles unmodified (but with many warnings) if you use f95. When the code is run it complains of a missing file. One can create an empty file of this name to keep it happy. In fact it fills the file with data. Then i
460.
by wbhart 15y ago
I work in academia as a mathematician. I maintain a library called FLINT (Fast Library for Number Theory).
461.
by wbhart 15y ago
It's remarkable that we refer to algorithms invented as "late" as the 90's as state-of-the-art. But sadly, it is so.
462.
by wbhart 15y ago
OK, after some effort I got the first of the MPQS programs to compile. Unfortunately it fails with a runtime error so I can't evaluate it. The program itself requires two files to exist before it can operate. Then it asks for the input numb
463.
by wbhart 15y ago
This is very interesting. Thank you for devoting your time to putting this on the web. Otherwise it might have rotted in your attic! It's unclear to me whether there is anything theoretically new in here yet. The algorithms are all familiar
464.
by wbhart 15y ago
I wonder if PayPal has misunderstood what Regretsy is doing. For example, suppose PayPal think that Regretsy is buying cheap toys at cost, marking them up for profit, adding the cost of shipping, then selling them to customers as part of th
465.
by wbhart 15y ago
Raising a base to a power is a prescription for how many times to multiply by the base. If you first raise it to one exponent, m say, then to another exponent, n say, and then multiply, you have first multiplied by the base m times, then mu
466.
by wbhart 15y ago
I'm sure it detects all manner of organic and explosive material, like fuel in fuel tanks, and brake fluid and sump oil, and shopping from the supermarket. Of course you should be able to shield yourself from the harmful effects of the X-ra
467.
by wbhart 15y ago
Oh! You thought they wanted to hire people who could crack actual real world cryptosystems.
468.
by wbhart 15y ago
Here's a good start to find out about the employer: http://www2.warwick.ac.uk/fac/soc/pais/people/aldrich/vigila... If they sound interesting to you then read the plenteous clues in the HN thread from this morning. It would be pretty hila
469.
by wbhart 15y ago
Why do you think this challenge has anything to do with xor'ing with a key? It's not that kind of code. Actually, I'd say that mob is after assembly language programmers at the moment, not people who know "basic cryptography and boolean alg
470.
by wbhart 15y ago
Sorry, I got confused there for a minute. The answer is in fact just "yes". I'm not sure why this was voted down. The reason is that the border rank of 2x2 matrix multiplication is seven. This was proved 5 years ago by Landsberg, though it
471.
by wbhart 15y ago
Yes.
472.
by wbhart 15y ago
Multiplying k arbitrary matrices can be done in less time than O(kn^omega). But certainly for k > 3 you wouldn't multiply naively k times as you've pointed out.
473.
by wbhart 15y ago
Actually, my statement about matrices of size 1.66x10^91 is misleading. As with Strassen this new bound is an asymptotic bound for the technique meaning that you technically need matrices of infinite size before you realise that complexity.
474.
by wbhart 15y ago
Yes, what you stated is not incorrect. The linked blog is not terribly clear on what has been done. Unfortunately what has been done is very subtle, so I can't really envisage a good blog article announcing this.
475.
by wbhart 15y ago
Ah yes, one can compute P(x) a polynomial such that P(A) = 0. If you wish to compute A^n for n much bigger than the degree of P you can compute S(x) = x^n mod P(x) and then just compute S(A). However, algorithms that do actually improve the
476.
by wbhart 15y ago
Yes, Strassen is straightforward to implement and makes a huge difference. Another practical algorithm applicable over small Galois fields is the "method of the four Russions" (none of whom are Russian). It's often used as a basecase for St
477.
by wbhart 15y ago
One cause of night sweats is a rare disease called Wegener's Granulomatosis, which is pretty treatable but sometimes gets misdiagnosed as cancer. It often seems to start as an ear infection or sinus problem and eventually causes scarring, l
478.
by wbhart 15y ago
Except that this algorithm can't be used for anything as small as n = 100. Essentially the analysis is asymptotic, meaning that you have matrices of dimension n = q^N and let N tend towards infinity to get your bound on omega.
479.
by wbhart 15y ago
You mean at most 2.3727. It's not really a safe assumption that the bound will shrink asymptotically to the real omega as far as I know. But it is suspected that higher tensor powers may drop the exponent slightly. I believe there are appro
480.
by wbhart 15y ago
That is sort of true. The approach to constructing an algorithm is not new, being essentially due to Coppersmith-Winograd. They used an algorithm A (which doesn't actually multiply matrices, but from which a matrix multiplication algorith

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