psykotic

53 ms·

421.
by psykotic 15y ago
> If you wanted to say that if's can be replaced with predicated instructions why such a convoluted example (which is a nice piece of code, by the way)? That's not what I wanted to say; it was a side note to a piece of code. Anyway, sor
422.
by psykotic 15y ago
> I admit I've overlooked the caveat while posting the response yet even with the caveat this does not make much sense, as every code can be turned into branchless when you use predicated instructions (a bit less so with conditional mov
423.
by psykotic 15y ago
I thought this caveat made it clear: > (In the binary search, you'd implement the if statements with conditional moves or predicated adds, depending on what your platform offers.) It's usually a bad idea to use arithmetical trickery in
424.
by psykotic 15y ago
There are many neat tricks for branchless algorithms. Once you get a feel for what makes them work, they're easy to invent on your own. Two representative examples: // branchless octree traversal i = x <= t->mx; i &#
425.
by psykotic 15y ago
> I personally find it difficult to read when each line of code is disjointed by comments I agree, but if you read any of Knuth's literate programs, they are not at all line-by-line commentaries.
426.
by psykotic 15y ago
The production costs for the first Shenmue game were in the neighborhood of 50 million dollars, which made it the most expensive video game at the time. A worthy sequel would take a lot of money to get made. I'd rather the series stay burie
427.
by psykotic 15y ago
Yes, it is one of the only countries left in the Western world that still has capital punishment on the books. But death is not mandated as the minimum punishment: "Whoever, owing allegiance to the United States, levies war against them or
428.
by psykotic 15y ago
The story has been around for a few weeks. As far as I know, his exact role at Kuma has not been publicly confirmed. But everything I've read indicates that he was hired for his military background and knowledge of Iran and Farsi to work on
429.
by psykotic 15y ago
Working for the military of an enemy state to undermine the government and instigate rebellion. I'm not making a value judgement. All I'm saying is that when you take everything into account, the legal charge isn't crazy. The punishment is
430.
by psykotic 15y ago
It gets worse. He held dual US-Iranian citizenships, so what he did was the textbook definition of treason, regardless of how you feel about Iran. If anything, this proves he is too stupid to have been very effective in his job as propagand
431.
by psykotic 15y ago
He wrote that code for his earlier course on geometric folding algorithms: http://courses.csail.mit.edu/6.849/fall10/lectures/ You'd enjoy it if you are into computational geometry.
432.
by psykotic 15y ago
What do you mean? If the original source is analog and sampled below its Nyquist rate in the analog-to-digital conversion, the process is indeed irreversible. But that all happens before any transforms from the time domain to the frequency
433.
by psykotic 15y ago
In the same genre and likewise in Haskell, I recommend Exploring JPEG: http://www.imperialviolet.org/binary/jpeg/ On the decoder side, for someone who has basic familiarity with compression and signal processing, the obstacles in understa
434.
by psykotic 15y ago
Your conclusion is right but your argument appears to be lacking. > You integrate this over the path that your center of mass takes, which is going to change linearly with your scale k (d). But if that's how you define d, then it is the
435.
by psykotic 15y ago
The very first function of the very first file I read had an algorithmic bug. It's dictGetRandomKey() in dict.c. First it finds a random occupied bucket by rejection sampling. Then it proceeds like this: /* Now we found a non empty bu
436.
by psykotic 15y ago
> current sandbox games (minecraft, dwarf fortress, terraria) implement water flows as cellular state machines. this is clearly wrong, because pressure is non-local Dwarf Fortress's algorithm actually supports global pressure propagatio
437.
by psykotic 15y ago
No, it is unstable. The striding means that two equal elements can easily be reordered. For example, after 2-sorting [(2,a), (1,b), (1,c)] by the first component you get [(1,c), (1,b), (2,a)].
438.
If correlation doesn’t imply causation, then what does?(michaelnielsen.org)
25 points by psykotic 15y ago|5 comments
439.
by psykotic 15y ago
Very nice. Since you asked for feedback, I'll say that the mix of narrative prose and line-by-line commenting of declarations is a bit strange. It's like it can't decide whether it's reference-style documentation, a literate program, or a s
440.
by psykotic 15y ago
Would you call a bunch of concentric circles a fractal? I hope not. The fractal dimension of such an infinite nesting is zero because the number of objects grows linearly with the level whereas the scale factor varies exponentially.
441.
by psykotic 15y ago
Why would they regret what they said? We should all be glad they called them out in such a public and unequivocal fashion. It means that scumbags might think twice next time before ripping off other people's work verbatim. Your response wou
442.
by psykotic 15y ago
Here's yet another proof. This one uses probability theory. Let's warm up with a probabilistic proof of 1 + p + p^2 + ... = 1/(1-p) in the form (1-p)(1 + p + p^2 + ...) = 1 This says that if you have a Bernoulli process wi
443.
by psykotic 15y ago
Not much of a lex fan. Here's a simple way to implement the indentation-to-braces transformation in a hand-written lexer: def tokenize(stream): indent = stream.indent while stream.current() and stream.indent >= ind
444.
by psykotic 15y ago
Nice trick. It works in any even base b: xy = b((x - b/2) + (y - b/2)) + (b - x)(b - y) For b = 2 in particular, x - b/2 and x - b/2 are the negative 1's complements of x and y, and b - x and b - y are the 2's complements. More gen
445.
by psykotic 15y ago
It does say something important about differentiation, which shows up very clearly and explicitly in the theory of generating functions and combinatorial species, and relates to my second proof. When you differentiate a type, you get the ty
446.
by psykotic 15y ago
A quicker proof is to just differentiate. For |r| < 1, we have 1 + r + r^2 + ... = 1/(1-r) Differentiate both sides of the equation: 1 + 2r + 3r^2 + ... = 1/(1-r)^2 Here's a bijective combinatorial proof, which I like
447.
by psykotic 15y ago
There's some sleight of hand here. Not all the digits are exactly right. Look how it skips from 997 to 999: http://www.futilitycloset.com/2012/01/08/math-notes-76/ Here's the math. Suppose you want a unit fraction 1/n with decimals that c
448.
by psykotic 15y ago
That function definition is a monstrosity because it is poorly factored. Assuming pre-existing fromBase and toBase functions, here is a definition that in my opinion is easily readable and matches your verbal description: halton b n =
449.
by psykotic 15y ago
> There was recently a very interesting post by John Carmack about static code checking, where he cited a great tweet by Dave Revell on code checking: "The more I push code through static analysis, the more I’m amazed that computers boo
450.
by psykotic 15y ago
Information-theoretic lower bounds are neat. Here's an even simpler example. In the decision tree model of computation (where decision nodes have constant degree), consider the problem of finding the value corresponding to a key in a dictio

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