nialo · HackerTrans

قبل 3 سنواتdiscuss

In case anyone here hasn't seen it, I want to share this very cool youtube series of an Australian clock maker creating a replica of the Antikythera device using only tools believed to be available to the ancient Greeks: https://www.youtube.com/watch?v=ML4tw_UzqZE&list=PLZioPDnFPN...

nialo

قبل 5 سنواتdiscuss

I want to second this, I worked as a mechanical engineer and never had accurate time estimates there either. Estimates of how long the work will take will be wrong whenever there are new problems to be solved, which is all engineering worth the name.

nialo

قبل 5 سنواتdiscuss

I spent some time helping someone get this set up for their music group, and it's really really nice just as a voice chat program. It's amazing how much of the unpleasantness of something like a Skype call goes away with really low latency

nialo

قبل 6 سنواتdiscuss

The vague impression I get is that maybe the answer is "Because Apple's software people and chip design people are in the same company, they did a better job of coordinating to make good tradeoffs in the chip and software design."

(I'm getting this from reading between lines on Twitter, so it's not exactly a high confidence guess)

nialo

قبل 7 سنواتdiscuss

I have walked out of pharmacies without buying Sudafed that I would have wanted because the "ask for a pack of Sudafed" step was too uncomfortable. Buying liquor is easier because I don't have to say words to explain what I want.

Edited to add: I'm not particularly up in arms about needing ID, and I feel like buying Sudafed got easier somehow recently, but this seemed like a place where I could help explain what sorts of things can be uncomfortable/difficult for some people.

nialo

قبل 8 سنواتdiscuss

I work on another music file management system, my personal special hell is playlist files. An m3u playlist file is just a new-line separated list of file paths, which can be relative or absolute, and potentially encoded in whatever locale is set on the users computer. Some fun issues:

* Windows and Mac filesystems are generally case-insensitive, so some users will have the file names in the playlist file in one case and the actual file names on disk in another format * Sometimes file paths cross between two different filesystems, because one is mounted in the other with a USB drive or over CIFS or similar. Sometimes these two different filesystems have different case sensitivities * There's no way to know how the playlist file was encoded * HFS+ normalizes file paths to Unicode NFD, but there's no guarantee that the paths in a playlist file will be normalized. Also, sometimes users generate an m3u file on a Windows system and expect it to just work on a Mac. Also, the filesystem nesting problem with network or USB mounts can happen this way too.

nialo

قبل 9 سنواتdiscuss

I switched also recently, the thing that helped me was adding this:

alias rg='rg -S'

to my .bashrc so that rg had the same default case sensitivity as ag.

nialo

قبل 9 سنواتdiscuss

In the spirit of learning about these things, you might want to try these: https://cryptopals.com/

In particular, problem number 17 from set 3 is an attack against CBC mode AES used with Mac-the-Encrypt. Maybe a fun exercise would be to first implement that attack against CBC mode, and then try to see if you can make it work against your CFB-HMAC protocol.

nialo

قبل 9 سنواتdiscuss

CVD in general is slow and time consuming, but because graphene is just one atom thick growing graphene specifically might not be too bad. Also the process gas/chemistry requirements are relatively very simple.

For reference, I used to see ~4 hour cycle times for growing graphene on copper sheets. I think most of that was in the heat up and cool down, maybe order of 30min actual growth time. These numbers might be off by a factor of 2-5, it's been a few years since that job, and I was a equipment design engineer not a process guy as such.

nialo

قبل 9 سنواتdiscuss

Asking honestly because I would like to know: What is wrong with writing a state machine using gotos? Assuming that one is solving a problem that definitely needs a state machine for some reason.

nialo

قبل 9 سنواتdiscuss

Do you know if this is still true with the newer "concurrent" garbage collector in more recent Mono versions? I work on an audio player app rather than games, but also have problems with the GC in Mono on IOS. We're hopeful that eventually they'll go away, but haven't tried again recently.

nialo

قبل 9 سنواتdiscuss

Have you tried implementing the length extension attacks?

Truncating from 512 bits to 256 bits hides 256 bits of the state from the attacker, so in order to use a length extension attack they would need to "guess" those bits.

nialo

قبل 9 سنواتdiscuss

In addition to being a better analogy, I am told it is possible to replicate the effect with a physical capacitor and a gas-discharge lamp: https://news.ycombinator.com/item?id=4600996

nialo

قبل 9 سنواتdiscuss

SHA-256 truncated to 224 bits is vulnerable to length extension attacks if the attacker can brute force the remaining 32 bits of the state. Some use cases will make this possible or practical, some will not. It depends on the details of the problem being solved.

nialo

قبل 9 سنواتdiscuss

This is somewhat self correcting.

HFT firms are make money by taking a spread, which is effectively the cost of making a single trade. As they compete and get better and better at there jobs, this spread well be reduced, the amount of money available to pay for the best and brightest programmers will come down, and they'll suck fewer of them away from other parts of the economy.

The point being, the further they go past this 'point of diminishing returns', the less money they can possibly make. To the extent that HFT is a zero sum game, there will always be a limit on how much money they can spend.

(I believe but cannot prove that this limiting effect has already started, HFT firms are consolidating and making thinner margins than they used to)

nialo

قبل 9 سنواتdiscuss

Is your suffix array implementation open source/available online anywhere? I'm always curious to see what other people's version of these sorts of things look like.

(I wrote an implementation of Ukkonen's suffix tree algorithm in C as maybe my second C program, it was pretty frustrating for a long time)

nialo

قبل 9 سنواتdiscuss

I haven't read this paper, and haven't worked with the compressed variety of suffix trees/arrays. That said, I'm confident it's possible to retrieve the original file from a normal suffix tree, although it would be pretty slow. I imagine it must be possible to retrieve the file from the compressed version as well.

If nothing else, I think it is possible to retrieve a complete file from any index that lets you search for substrings and get a full string and position in the file back. Just search for all length 1 substrings, get a map from position -> string, then reconstruct the file from that.

I doubt it's worth storing files this way, because turning the index back into the file sounds very slow. I'd rather just store the file and the index, the time v. space tradeoff seems like a good one if you really care about search performance. That said, I use The Silver Searcher, and it's fast enough with no index that I don't think any of this stuff is worth the effort for searching text files on a file system.

nialo

قبل 9 سنواتdiscuss

They solve different problems. In particular, ripgrep and friends are designed to search arbitrary and potentially large directories with no pre-computation. They run in time ~linear in the size of the files to be searched.

The paper under discussion here is about a new way to create an index that also takes time ~linear in the size of the files to be searched, although presumably with a higher constant factor than just searching those files. After you have the index it's possible to search it in time linear in the length of the query rather than the files. This is much faster, but requires storing an index that is at least as large as the original file set, and keeping it up to date as things are changed etc.

nialo

قبل 9 سنواتdiscuss

Asking because I don't understand:

What's the difference between the seller owing me money back and me having a property right in that money? They seem similar to my not-at-all-a-lawyer intuition, what am I missing?

nialo

قبل 9 سنواتdiscuss

I wasn't particularly talking about software engineers. I have a mechanical engineering degree, and none of the ~20ish engineers at the first place I worked had a PE licence. If you want "engineer" in a job title to mean "has a PE licence", you're going to need to change the title of perhaps 95% of people currently employed in mechanical or electrical engineering. Probably more than ninety percent of aerospace engineers too. There is maybe an argument to be made that programming shouldn't be called "software engineering", but this really isn't it.

Also for whatever it is worth, I've now worked in mechanical engineering for 5 years and software for about 1 year, and they both feel the same to me. Software is sometimes faster and sloppier, but I think that's just because the build process for a program takes minutes and the build process for the CVD machines I used to design takes months.

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