What resources you guys use to hire freelancers? - <AUTHOR>

I have mostly used odesk.com (because there are lot of people over there) to hire free lancers. I have seen most of them are crappy. They are just there to take your money and no worries about the deliverables. Applicants will try to negotiate on your total budget and will ask for 30%-40% advance. It's upto your negotiation power and you might be successful in bringing the advance to just $30-$40 and once they take that, they are gone.
I have lot of ideas (iphone apps, websites) . I am not looking to hire a dedicated full time team, just free lancers - billed on a fixed budget.
Please let me know what resources you will suggest to look and please share your experiences also.
Much Thanks. <comment><USER2> Odesk, but with a few must-do approaches:

 _Hourly only, with work tracking.

_ Limit the hours authorized to just long enough to figure out if they're worth their rate (2-3 is what I use), then up them only when you like a candidate

 _If a task is important, hire the best 3 candidates to do the first two hours' worth. Usually 1 will totally flake somehow, 1 will almost do ok, 1 will be good.

_ Weigh heavily on iterative solving (inspect their work daily (archived attachments are a must), interact, and don't give them too long of a to-do list)

 _Avoid skype and off-oDesk emails; it's always good to keep things in writing to maintain perspective

_ Recognize that they have other projects going on and that you can't occupy the lowest-bidder and highest-priority spaces at the same time (though one or the other isn't too much to expect)

*Don't be afraid to walk away and stop throwing good money after bad if performance suffers (usually that means they get unresponsive or slow to return work)

</comment><comment><USER3> There's a monthly HackerNews thread for people seeking freelancers and freelancers looking to get hired. The thread is usually titled "Freelancer? Seeking freelancer? (month year)"

I think that might be worth checking out. The rates will probably be higher than the ones on odesk.com, though.

<comment><AUTHOR> Thanks, I will look into that thread.

</comment></comment><comment><USER4> I'm in the process of creating a new dev team (A small one), would you be interested in working with one of our developers? We can discuss negotiations via e-mail :)

</comment><comment><USER5> Have you thought about building it out yourself? I know a few business folks who taught themselves enough programming to get a website built out.

<comment><AUTHOR> Thanks for replying. I am coding for two websites already. Coding for iphone means first I have to learn objective-c, xcode and lot of other things along the way.

I think delegation of work is a great idea instead of doing everything by yourself, IMHO.</comment></comment>


How One Man Confused Grocers and Won Customers with Canned Pancakes - <AUTHOR> http://www.fastcompany.com/blog/chris-dannen/techwatch/how-one-man-confused-grocers-and-won-customers-pancakes-can <comment><USER2> "The problem: supermarkets don't have a section for frozen breakfast goods."

Huh? Every grocery I can recall has had an aisle full of frozen pancakes, waffles, sausage, etc.</comment>


Price of LEDs falling so fast it's profitable to farm in a New Jersey nightclub - <AUTHOR> http://qz.com/705398/the-price-of-leds-is-falling-so-fast-its-profitable-to-farm-in-a-new-jersey-nightclub/ <comment><USER2> Article sounds like LED commercial.

What's the problem with sunlight farming?

If you want to try that at home, be aware of mold.</comment>


French Constitutional Council Widely Approves Surveillance Law - <AUTHOR> http://www.laquadrature.net/en/shame-on-france-french-constitutional-council-widely-approves-surveillance-law

<comment><USER2> (French here). This is a really sad day for the country. I don't really know what to add here to the conversation, it was pretty much expected after the massive amount of laws during the past 10 years that tried to limit freedom of speech and increase the surveillance, it's just the next step.

The country has just reached a new low. I just hoped until the end that it would not pass but I was delusional. As a side effect, it's also going to destroy the few technological businesses we had left, like they needed that... I was really hoping that things would change and that the country could finally take advantage of massive amount of bright minds we have here... So much potential is wasted... Anyway, that will be for another year...

<comment><USER3> (Russian here). I so much understand you brother (or sister). We've got an even harder wave of prohibitive laws and the local IT industry has been brought to its knees. Companies have been leaving, people have been leaving. I haven't seen any appealing job openings for close to two years. I myself am thinking of emigrating, even thought about France, but now I'm not sure it was such a good idea.

>> So much potential is wasted... That's the most tragic thing indeed. You can import food, clothes, cars and so on but you can't import talent. When it goes, it's final.

<comment><USER2> Thank you for this comment. I guess you can understand how depressing it sounds, I go back in France every 2/3 months and everything is worse everytime I go there, and I can do nothing about it. It's really crashing at high speed.

I also have a friend in Moscow I discuss with regularly. I can speak basic Russian but I don't mention it normally because it's really a Tarzan-like level, the language is really beautiful. I really hope things are going to improve there also. France is definitely not the place to go for IT, I'm sorry for that.

<comment><USER3> I'm sorry you're going through that kind of feelings, they're pretty heavy to live with on a daily basis. A month under that stress counts almost as a year.

I've always liked France and its culture, and I speak French on some level, I guess that's why I take personally all bad things that I hear from France, as if they concerned mon pays natal.

If you'd like we could exchange privately, I could attempt to cheer you up (from the position of a person living in a place that has fallen much lower than yours), though I realize there's not much I can say to remedy the gloom you're seeing around you.

<comment><USER2> Thanks, we could have some discussion sometimes, you can reach me at my email address (on my profile), I cannot guarantee that my Russian will be good enough for a conversation but I will try !

</comment></comment></comment></comment></comment><comment><USER4> The education France has provided me with would probably have cost me much more anywhere else in the world. I have always wished to stay here to work, if only to pay some of it back to my country. With a degree in the STEM fields, I expected it would be easy.

I did not expect political issues to get in the way. I did not think the misuses of our surveillance system would one day be even remotely on par with those of the US or the UK, to the point that I do not know today where my privacy is breached the more.

Of course we say "let's encrypt", we foster the use of Tor and the likes, but that misses the point. There should not even be a case for such a law which will help nothing but totalitarianism and is even a disincentive to investments in France. Still our politicians and administrations have paid little heed to La Quadrature du Net's and other actors' comments. Instead the government drafted this law in haste, seemingly to curtail the democratic process which should have taken place in its entirety, especially for a change that big regarding our freedom.

The way I see things, I have two options: leave for another country that still deems privacy as a fundamental liberty, or stay in France and get involved in politics in the hope that I can help reverse the current situation.

I do not think I have the skills to get involved in politics, nor do I have the desire to. I guess I will soon be part of their statistics on "brain drain", although right now I feel more ousted from France than attracted to anywhere else.

<comment><USER5> Well articulated.

I feel similarly about Sweden. But assuming one does pack up and leave, where would one go? Without doing any real research on it I would have hoped that France, with it's strong historical record on liberty, would be a reasonably good option within Europe, but it seems that may have been no more than wishful thinking on my part.

<comment><USER6> > But assuming one does pack up and leave, where would one go?

That is an extremely good question and one that I've spent considerable time and funds on trying to answer.

In short:

Nowhere. There isn't a country that does not have some critical flaw in their political system. If a country without such flaws were come into being it would not last because a country that would 'play nice' with its citizens and that would be efficient with its funds would be over-run by more aggressive neighbors unless it were heavily fortified by natural barriers.

The countries that come closest to this in the world today are Iceland and Switzerland.

</comment></comment></comment><comment><USER7> And what is even more worrying is that the examples of abuse of surveillance laws have been frequent.

President Mitterrand was spying on anyone who could expose his lies (bigamy, fake medical certificates). President Hollande was spying on the discussion between former President Sarkozy and his attorney.

Even in the US, president Obama was using his own surveillance powers to expose the sources of political journalists.

It doesn't take a lot of imagination to consider how badly these laws can be abused.

<comment><USER8> Is it just as valid to say that Obama's _administration_ was using its surveillance powers to investigate journalism sources that had _straightforwardly broken the law_ by leaking classified information? James Risen is the most famous of these cases, and his indicted source leaked _counterproliferation secrets_.

I agree that surveillance authority should be tightly restricted, far more than it is today.

I'm just on false-equivalence watch. The investigation of Jeffrey Alexander Sterling does not sound equivalent to a sitting head of state snooping directly on his political rival and their lawyer.

<comment><USER7> I don't think that in any of the cases I mentioned the president himself was literally listening to some tapes.

And the protection of the sources that journalists enjoy is precisely because people leaking information to journalists are breaking laws and internal policies and would fear reprisals otherwise. This is an important counter- power.

<comment><USER8> Our law has for the most part never recognized any kind of privilege for journalists and their sources. Protection of sources is more like a code of conduct among journalists, not a part of the broader social contract.

To me, this makes sense. Literally anyone can be a journalist. Nobody elects them, and nothing but the market has any voice in what they do. I think it's better that way, too: you can see how fraught government involvement with even the most reputable state-sponsored media outlets can be.

<comment> loup-vaillant I agree with your main point, but:

> _nothing but the market has any voice in what [journalists] do._

That "market" is pretty specific, and has a strong voice, though. Most media are owned by a few big corporations, and basically say what those corporations will allow them to say. Those who don't quickly find it much harder to sell ad space, their main source of income.

Corporation-sponsored media are structurally just as bad as state-sponsored ones. For practical purposes, they might even be a bit worse.

One way or another, independent journalism needs independent income.

<comment><USER9> Independent from what? I hear that rhetoric a lot in France from people who read Mediapart, an "independently funded" newspaper and website. Their slogan is something along the lines of "Only our readers can buy us."

I always found it quite ironic that their readership seems to feel like that guarantees impartiality.

On the subject of media bias, I suggest reading Matthew Gentzkow's work or even just a survey like this one: [http://scholar.harvard.edu/files/shleifer/files/shleifer_cor...](http://scholar.harvard.edu/files/shleifer/files/shleifer_corrected_proofs_1.pdf)

TL;DR: Nope, ownership isn't the main factor in media bias.

"As important, Gentzkow and Shapiro [6] show that, after controlling for a newspaper's audience, the identity of its owner does not affect its slant.1 Two newspapers with the same owner look no more similar in their slant than newspapers with different owners. Ownership regulation in the US and elsewhere is based on the premise a news outlet's owner determines how it spins the news. Gentzkow and Shapiro produced the first large-scale test of this hypothesis, which showed that, contrary to the conventional wisdom and regulatory stance, demand is much more influential in shaping content than supply as proxied by ownership."

<comment> loup-vaillant > _Independent from what?_

I don't know. I had 2 solutions in mind, and the rest of your comment suggests having the readers pay for the media doesn't work. The other solution I though of was basic income (it's the solution for many things.) Looks like true independence only comes from "fuck you money", that basic income would provide.

That said, even if your quote is accurate, owners of journals can just drop support if they notice they're talking to the wrong audience.

</comment></comment></comment></comment></comment></comment></comment><comment> loup-vaillant (French here.)

I guess this is time to escalate. Let's encrypt as much as we can. And maybe prepare for physical violence. This may get ugly in a few years.

<comment><USER3> From what I heard French are obliged to surrender encryption keys at the request of authorities or go to jail for a few years for denying their request. The only thing that may be left is to pack your things and go.

<comment><USER10> Correct. [http://www.legifrance.gouv.fr/affichCodeArticle.do?cidTexte=...](http://www.legifrance.gouv.fr/affichCodeArticle.do?cidTexte=LEGITEXT000006070719&idArticle=LEGIARTI000006418646&dateTexte=&categorieLien=cid)

<comment><USER11> You don't have to surrender the key, but you are required to at least decrypt things for the authorities.

However, I the twist seems to be in the word "susceptible": any encryption key is susceptible to be somehow used to commit a crime, while on the other hand a jury would probably "deny a request" of the authorities if they can't show enough evidences.

</comment></comment></comment></comment><comment><USER12> I think this is awful, but is it _wrong_ in the context the council was working in?

More specifically, consider how the US Supreme Court works. The Court's job isn't to decide what side is good and what side is evil. Their job is to determine what side is in accordance with the law, and if that law is consonant with our Constitution.

How similar to this is the French Constitutional Council? Were they given no choice, and forced to make an ugly decision because it is, indeed, what their Constitution allows?

If so, the answer isn't to bemoan the decision and criticize the Council, but to find a way to fix the French Constitution so that it no longer supports this decision.

<comment> loup-vaillant Having loosely followed the QPC that has just been rejected, I think it's pretty clear they had a case.

We should also see the details of this decision. They may have interpreted the law (and documented that interpretation) in a way that makes it less unacceptable.

Also, there will a couple other recourse for that same law. It's not over yet.

</comment></comment><comment><USER13> "1984" is not only an instructional manual now, it has become a political must-have. At least in the US we have lip-service to privacy and freedom of thought.

</comment><comment><USER14> Can anyone offer a detailed explanation of what the French Government has implemented?

There is a large movement in france to use encryption software. Hopefully this just fuels the fire.

</comment><comment><USER15> "socialists"... more like fascists. A sad day indeed.

<comment> loup-vaillant First, there is no connection.

Second, the only thing socialist about our government is the name. They're capitalists like the other big party.

<comment><USER16> Wiki: Capitalism is an economic system and a mode of production in which trade, industries, and the means of production are largely or entirely privately owned.

This is France is it?

<comment><AUTHOR> He probably meant that they prefer to serve the interest of big economic groups/industries above the people in the country they are empowered to rule.

<comment><USER17> I think that is generally referred to as "Corporatism" these days.</comment></comment></comment></comment></comment>


Gilbert Strang Teaches Linear Algebra - <AUTHOR> https://ocw.mit.edu/courses/mathematics/18-06-linear-algebra-spring-2010/video-lectures/ <comment><USER2> I wish I had this when I was learning Linear Algebra. When it was taught to me, both in HS and College, there was not a word of motivation about why we were juggling numbers around in boxes. It was tedious and had seemed to have no connection to anything.

I developed a strong dislike for LA, if not outright fear and hatred. This from someone who majored in math at university. I later learned from reading Dr Oakley's book, _A Mind For Numbers_, that this is a perfect recipe for not mastering a subject. I was sabotaging my own learning by approaching it from the point of view of something to be despised. It was many years later after reading Oakley's book that I challenged myself to learn Linear Algebra.

I found the Coursera course Coding the Matrix [https://codingthematrix.com/](https://codingthematrix.com/) perfect. Not only did Professor Philip Klein explain the subject well, but it was also a programming course in python. Coding the algorithms helped make them that much more concrete. I'm happy to say I finished the online course with 100% grade.

Unfortunately Coding the Matrix is no longer available on Coursera.

I know this thread is more about Strang being a teaching god, and he is. I wanted to add something on alternative ways to learn linear algebra.

<comment><USER3> This is a problem I always had in university. Higher math always seemed to start with "the definition of X is Z etc." and I would never know what's the purpose of doing this. When I attended a talk of Gilbert Strang many years later it was eye opening because it was a totally different approach that always accompanied theoretical concepts with a concrete interpretation.

Actually I now think it might also be a cultural thing. If you take a look at the approaches the English Wikipedia takes vs. the German Wikipedia take explaining a vector space you'll know what I mean:

[https://en.wikipedia.org/wiki/Vector_space#Introduction_and_...](https://en.wikipedia.org/wiki/Vector_space#Introduction_and_definition)

[https://de.wikipedia.org/wiki/Vektorraum#Definition](https://de.wikipedia.org/wiki/Vektorraum#Definition)

<comment><USER4> I'd second the point on different cultures doing it differently. One of my profs once said he had a book written by two mathematicians, one German and another Italian. It was fairly evident who had worked on which part. He also mentioned that the "old style" German books would almost apologize if they "had" to use just a few pictures to illustrate something.

</comment></comment></comment><comment><USER5> I used this course years ago while I was self-teaching CS, really great course. MIT in general makes some awesome stuff available -- so awesome, it helped this disgruntled lawyer get the hell out of law and into my dream field.

I can't express strongly enough how appreciative I am to MIT, and also schools like Stanford and Harvard, and Prof. Sedgewick from Princeton, for making courses like this publicly available.

<comment><USER6> I'm also a (formerly disgruntled) lawyer eternally grateful to Stanford and MIT for helping me escape. And like you, I cannot overstate my appreciation. If anyone involved in these courses stumbles upon this thread - thank you.

<comment><USER7> I've been on the other side (CS professor for two years, apparently students really loved my work) - if you can, email them and tell them about your appreciation. It's worth it.

I don't know about others, but in my case I had to put up with a lot of BS, and "older" colleagues that were envious of my "performance" (annual feedback reviews by students). These few emails (and two letters!!) went a long way for me.

<comment><USER8> I will do that! OCW, and Princeton Coursera have enabled me to do far more than I ever thought was possible as an immigrant kid.

</comment></comment></comment></comment><comment><USER9> He has another advanced Linear Algebra class:

[https://ocw.mit.edu/courses/mathematics/18-065-matrix- method...](https://ocw.mit.edu/courses/mathematics/18-065-matrix-methods-in- data-analysis-signal-processing-and-machine-learning-spring-2018/)

And this new book:

[https://www.amazon.com/Linear-Algebra-Learning-Gilbert- Stran...](https://www.amazon.com/Linear-Algebra-Learning-Gilbert- Strang/dp/0692196382/)

<comment><USER10> These lectures are really excellent.

Packed with insight that would otherwise take years to pick up piecemeal elsewhere.

</comment></comment><comment><USER11> Gilbert Strang got me through linear algebra in University. Fifteen or so years later, I told my wife who went back to school as an older adult about him. He got her through, too.

His teaching capability is so great, we ended up buying his textbook and using that instead of the one assigned by her college. My wife ended up with the best grades in the class, but not only that, ended up actually learning the material and retaining it many years later. Her field is in no way related to mathematics, but it would not be an exaggeration to say that she benefited greatly from her maths exposure.

Linear algebra, heck yeah! Thank you, Dr. Strang.

</comment><comment><USER12> Related note: Strang's essay on the imbalance in education in favor of Calculus over Linear Algebra is (in my opinion at least) a great read, for those interested in the pedagogy of mathematics.

[http://web.mit.edu/18.06/www/Essays/too-much- calculus.pdf](http://web.mit.edu/18.06/www/Essays/too-much-calculus.pdf)

<comment><USER13> I think Strang's videos should also be used as examples of all around great pedagogy, independent of the Linear Algebra content.

He does more with some chalk and a big black board than any modern courses using fancy presentation technology.

<comment><USER14> Definitely - I went through some of his lectures after I had read up on Linear Algebra as part of a course (from [1]) and had used it in a bunch of applications, but I still found the lectures worth going through if only because his fantastic exposition helped me visualize things better.

[1]we followed Huffman-Kunze [https://www.amazon.com/Linear-Algebra-Kunze- Hoffman/dp/93325...](https://www.amazon.com/Linear-Algebra-Kunze- Hoffman/dp/9332550077)

</comment></comment></comment><comment><USER15> At a different college, I loved that class. It brought equations to within a hair's breath of symbolic data for me in 1+ dimensional arrays. It was absolutely essential for the honors chemistry/physics/compsci track.

I had an HP 48G calculator at the time that could do symbolic derivation and all of the matrix decompositions. And if it didn't have a function, it was easy to write your own in any of four (4) programming languages: symbolic user programs (User-RPL), their compiled language (System-RPL), C or assembly. The matrix editor looked exactly like a spreadsheet. What's cool about HP's Erable (CAS) is, just short of being LISP/Scheme, everything was a value. Compiled binaries could be pushed on the stack (RPN). Oh and programs could be copied to other HP 48G/GX's with it's incredibly-powerful serial IR port. Some ingenious soul figured out how to turn the calculator into a _learning_ IR remote control with a library of preset manufacturer codes. (I once turned on all the TVs in the lecture hall from the back of the class (15 m away) with my calculator during lecture... and people freaked out. :D) People modded them with 2-8x as much memory by chip stacking and wiring the enable pin and an inverter to the processor. None of this 64KiB rubbish, 512KiB FTW. And if you couldn't see parens in your 3 line equation, there's a graphical equation editor. Finally, if you got bored of that, there's always the easter eggs with the team's name in a solved crossword puzzle and grayscale pictures of them (not like Tetris on an Agilent oscilloscope, but okay).

I preferred his competitor's book because it made sense to me, Anton's _Elementary Linear Algebra, Applications Version_

His book is _Introduction to Linear Algebra._

</comment><comment><USER16> Strang is an excellent teacher and this an effective course for coming up to speed in Linear Algebra fundamentals.

I watched every lecture and did most of the homeworks a couple of summers ago in preparation for taking grad ML courses at Carnegie Mellon (10-601 Intro and 10-605 Scalable ML). The foundations that I built from Strang's course were essential to my success later.

<comment><USER17> Exactly this. I also studied from his video lectures and I owe most of my understanding of the topic to him. He has an amazing ability to intuitively explain complex concepts step by step.

</comment></comment><comment><USER18> This is an excellent course. That's where I first learned about the "column picture" of matrix multiplication... and this after 10+ using linear algebra and teaching. Overall LA can be a complicated subject, but Strang does a good job at making it seem like common sense.

For more linear algebra goodness, check out the 3Blue1Brown playlist, which provides a lot of the important geometric intuition: [https://www.youtube.com/playlist?list=PLZHQObOWTQDPD3MizzM2x...](https://www.youtube.com/playlist?list=PLZHQObOWTQDPD3MizzM2xVFitgF8hE_ab)

Another good book with visuals and manipulatives is [http://immersivemath.com/ila/index.html](http://immersivemath.com/ila/index.html)

And this is a short tutorial that I wrote that summarizes some of the main ideas of LA in just four pages: [https://minireference.com/static/tutorials/linear_algebra_in...](https://minireference.com/static/tutorials/linear_algebra_in_4_pages.pdf) You can print this and enjoy with your weekend coffee tomorrow. For bonus points, you can also learn how to do LA using SymPy here [https://github.com/minireference/sympytut_notebooks/blob/mas...](https://github.com/minireference/sympytut_notebooks/blob/master/notebooks/Linear- algebra.ipynb)

</comment><comment><USER19> G-Strang! I took this class in the fall of 1999, and I remember thinking it was unusual that every lecture was being recorded. So cool to see it still having an impact 20+ years later.

</comment><comment><USER20> Gilbert Strang got me through the more difficult of the two linear algebra gatekeeper classes in University. I didn't go to class once after the first week. I sent him a thank you email and he wrote a nice reply.

</comment><comment><USER21> These videos helped me immensely when I was getting my Electrical Engineering degree. I didn't realize going into the degree a bulk of the coursework would be focused around fourier/laplace transforms and linear algebra.

</comment><comment><USER22> I am not able to wait for a video to explain something, I prefer to read books. I don't know what is good about this teacher. Linear Algebra Done Right is a good book. I am not able to appreciate Gilbert Strang style. But algebra is easy to grasp if you are motivated and prepared for hard work. I recall he stressed SVD. Once you are up on statistics SVD is a very useful tool, but I find his style overly pragmatic, if you are able to read a book like Linear Algebra Done Right you will appreciate what a non pragmatic style mean here. Anyway this can be sour grapes, I would like my students to enjoy my lessons. Algebra Done Right goal is that you can demonstrate and learn for facts and proofs. GS book is about using the tools of linear algebra.

</comment><comment><USER23> I'm a current CS student. I've heard that Linear Algebra is a worthwhile class for students studying Computer Science. Yet, my program doesn't have it as a requirement. Can anyone explain in broad terms if this course is something I should consider taking anyways?

<comment><USER24> If you ever intend to have anything to do with machine learning, computer graphics, or work for a quant firm[1], yes.

If you want to work on adtech, CRUD apps, or uber-but-for-catsitters startups, probably not. I have been working on two out of the three for a decade, and in all this time, I haven't had to use a lick of linear algebra.

From an academic standpoint, it's arguably a more useful course for your general education than calculus (Which is a requirement for just about any degree), but less useful than statistics.

[1] If you ever intend to work for a quant firm, you should probably take a lot more math courses than just linear algebra.

<comment><USER25> Adtech does a lot of machine learning, so at least a surface level understanding of linear algebra is useful there.

<comment><USER24> Of the ~100 people in my immediate work area who work on a large ads product, about 4 of them do ML.

The overwhelming majority of adtech is like any other enterprise business - building CRUD apps.

</comment></comment></comment></comment><comment><USER26> Gilbert Strang has this lovely patrician, avuncular energy that puts me at ease. I feel like he's as likely to pour me a cup of tea as he is to expound on matrices. He feels less like an MIT professor and more like a shared pedagogical treasure of our internet age.

</comment><comment><USER27> I have always thought that the best way to learn linear algebra would involve constant visualization and interaction on a computer.

My LA teacher in college told us that he visualized the left matrix in a matrix multiplication flipping over and crashing down on top of the right matrix. (or is that backwards?) The only way I learned things like vector spaces and orthogonality was by visualizing them in my head, Bret-Victor style.

In my totally unqualified opinion, there is a huge opportunity for a software product that allows people to play with and explore mathematical concepts in a visual and fun way.

<comment><USER28> > the left matrix in a matrix multiplication flipping over and crashing down > on top of the right matrix. (or is that backwards?)

Both ways work. A row from the left matrix rotated 90° clockwise to line up with the rows of the right matrix gives you the coefficients to use to combine those rows into a row of the result matrix. Conversely, a column from the right matrix rotated 90° anticlockwise to line up with the columns of the left matrix gives you the coefficients to use to combine those columns into a column of the result matrix.

I didn't fully understand that until I read Strang's book.

</comment></comment><comment><USER29> This course was a godsend for me.

Before I dropped out of FSU, I managed to rope myself into two math classes (Complex Variables and Game Theory), both of which had a strict requirement of Linear Algebra, which I hadn't taken.

I was a bit panicked because it was a bit too late to sign up for anything else, and so I binged through this MIT course, and learned _just enough_ to get permission from both the professors to still let me take the classes. It definitely would have been _better_ to have taken linear algebra directly, but having this as a resource was super valuable.

</comment><comment><USER30> I watched a few of the lectures in the past. I was really impressed with his teaching skills but the quality of some of the videos was really bad it really took away from the learning experience. Really wish there could be a professionally recorded version of him.

</comment><comment><USER31> Linear Algebra and it's Applications, a textbook by Gilbert Strang was the most entertaining textbook I've ever perused in engineering.

He has a great sense of humour and keeps slipping jokes in unexpected places.

</comment><comment><USER32> I watched these lectures the summer before starting university as Linear Algebra was one of the mandatory courses for the first semester.

These are by far the best lectures on Math/CS I've ever seen. Helped me A LOT.

</comment><comment><USER33> Is there a text focusing on the known differences between the lower dimensional spaces of 1-4 dimensions and the higher-dimensionality spaces commonly used in DNN calculations?

<comment><USER34> You might have to be a bit more specific about what exactly you are asking, but for example this paper and its references might be an interesting start: [https://bib.dbvis.de/uploadedFiles/155.pdf](https://bib.dbvis.de/uploadedFiles/155.pdf)

</comment></comment><comment><USER35> I learned from his videos almost 10 years ago. Amazing professor, I really need to check those videos again.

</comment><comment><USER36> UC Berkeley vandalized their historical video lecture collection by deleting it in response to a government ADA enquiry and pressure from "progressives" on campus. Does anyone known why videos like those of Strang at MIT haven't had the same fate?

</comment><comment><USER37> This saved me in college

</comment><comment><USER38> The website is currently unreachable for me.

</comment><comment><USER39> For anyone using these videos now to help them learn linear algebra, id like to suggest a FULL STOP and watch this YouTube playlist FIRST.

Strang is absolutely enlightening but I found it incredibly moreso after watching 3blue1browns series on visualizing linear algebra[https://www.youtube.com/playlist?list=PLZHQObOWTQDPD3MizzM2x...](https://www.youtube.com/playlist?list=PLZHQObOWTQDPD3MizzM2xVFitgF8hE_ab&app=desktop)

</comment><comment><USER40> Cautionary note: you might better look for another resource to learn linear algebra. Don't waste your time watching these videos just because it is from MIT

<comment><USER41> Strang in general, and these videos in particular, are strongly recommended every time self-teaching linear algebra comes up here. In 13 years on hacker news I think this is the first negative thing about Strang I have read. Can you expand on your criticism?

<comment><USER40> Strang course is too verbose and one does not need the whole course to do practical work. Linear algebra done right is the book you need if you want to apply in practice rather than just watching mit videos. [https://www.amazon.com/Linear-Algebra-Right-Undergraduate- Ma...](https://www.amazon.com/Linear-Algebra-Right-Undergraduate- Mathematics/dp/3319307657/ref=asc_df_3319307657_nodl/?tag=hyprod-20&linkCode=df0&hvadid=312152840806&hvpos=&hvnetw=g&hvrand=4114625584809220351&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=1014226&hvtargid=pla-684058077792&psc=1&tag=&ref=&adgrpid=61316181319&hvpone=&hvptwo=&hvadid=312152840806&hvpos=&hvnetw=g&hvrand=4114625584809220351&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=1014226&hvtargid=pla-684058077792)

</comment></comment></comment><comment><USER42> I wonder if all the teachers in MIT are as good as him?

</comment><comment><USER43> How important is Linear Algebra for day to day work in FANG companies?

<comment><USER44> Not. It's an extremely fundamental area of mathematics, necessary for really understanding any mathematical subject (including statistics, machine learning, signal processing etc) but it's not at all necessary for the vast majority of programming / software engineering tasks, and indeed you'll find excellent software engineers who haven't got a clue about linear algebra. I think the reason you see it discussed on HN is because many people here are interested in mathematics and that sort of theoretical way of thinking.

I don't mean to sound negative about it though. For example, the notions of abstraction and interface are very important in both maths and software.

</comment></comment><comment><USER45> People frequently recommend Strang's teaching as an amazing pedagogical approach for engineers and applied mathematicians, but I find I'm frustrated every time I read his books or listen to his lectures. They don't work well for me and I've found much better alternatives

<comment><USER46> Sharing those alternatives would be a more valuable comment.</comment></comment>


Node.js: Annotated Tutorial - <AUTHOR> https://github.com/MartinChavez/Node.js-Tutorial <comment><AUTHOR> _Node.js: Tutorial_

Use this tutorial as a guide to learn Node.js. Each unit contains an annotated lesson with working examples.

Topics:

* Introduction

* Events

* Streams

* File System Manipulation

* Uploading Files

* Modules

* NPM

* Express

* Express Routes

* Socket.io

* Persisting Data with Redis

[https://github.com/MartinChavez/Node.js- Tutorial](https://github.com/MartinChavez/Node.js-Tutorial)

</comment><comment><USER2> Thanks.</comment>


Good Words Gone Bad - <AUTHOR> https://www.reddit.com/r/PhantomForces/comments/4nwnnt/on_the_thirdparty_chat_filter/?st=irnqg2uk&sh=ab0e2f8d <comment><USER2> My son plays Roblox and this is definitely a big issue. I basically had to turn off his filter so he could play the game. Otherwise, the chat looks like this:

Player1: "Can you promote me?" Player1: "Did you see that?"

Player2: "Yeah, just send me a message" Player2: "Did you see that?"

Player1: "Thanks!" Player1: "Did you see that?"

Pretty frustrating, even for a parent. Seems like their filtering technology is just a total piece of junk.

<comment><USER3> What happens when you turn it off? Does that mean your child can say anything and receive anything from another user? Or is the incoming chat still filtered?

</comment></comment><comment><USER3> How can filter tech still suck so bad? My kids can't even use their chat without looking they speak in hash tags.

Did they build this in house?</comment>


WSJ Launch Wikileaks killer - and reserve rights to out whistleblowers - <AUTHOR> http://alexblom.com/blog/2011/05/wall-street-journal-launch-wikileaks-killer-and-promise-to-out-you-in-the-process/

<comment><USER2> How is this a "Wikileaks killer" then? The essence of Wikileaks is in how they protect their sources.

<comment><USER3> That's the point of the article.

<comment><USER2> Then why call it a "Wikileaks killer" in the title of the article?

<comment><AUTHOR> The intent seems to be a misguided attempt to do as much.

</comment></comment></comment></comment><comment><USER4> More like whistleblowerleaks. Sounds like a honeypot for the unwary whistleblower.</comment>


Ranking of the top US women startup founders and entrepreneurs (2018) - <AUTHOR> https://qz.com/work/1372695/the-founders-index-a-rising-generation-of-female-entrepreneurs-in-the-us/ <comment><USER2> ok?</comment>


Codidact – A community run stack exchange alternative - <AUTHOR> https://codidact.org/ <comment><AUTHOR> This is currently a WIP and things are moving quite fast!

Feel free to join, help, and contribute.

We have a lot of good issues for people new to open source, so this is a great project to begin your open source career.

I also want to clarify that this is fully open source and community run, no money hungry corporation behind it.</comment>


Free HTTPS: Three Paths - <AUTHOR> https://fly.io/articles/free-https-three-paths/ <comment><USER2> You forgot Firebase: free hosting and free https certs for your domain with a 1-click procedure on any of their tiers (included the free one).</comment>


Zulu, Xhosa, Swati, Hlubi, Phuthi and Ndebele - <AUTHOR> http://en.wikipedia.org/wiki/Nguni_languages

<comment><USER2> I spent awhile in South Africa studying public health back when I was in school and as a result, learned Xhosa.

Very fun to learn (grammatically fairly straightforward, but making all the sounds correctly is a bit challenging) and being able to speak a language with clicks is always a good party trick.

Miriam Makeba is the most well known Xhosa singer, but if anyone is interested in listening to some other music, Pitch Black Afro and Hip Hop Pantsula are good examples of modern SA hip hop/kwaito music. Not 100% Xhosa - both also mix in some of the other languages mentioned in the wiki entry.</comment>


Certain IT skills in demand despite economy - <AUTHOR> http://www.infoworld.com/article/09/02/03/Certain_IT_skills_in_demand_despite_economy_1.html

<comment><USER2> To spare you the into ad, animation, and low signal to noise ratio:

Up: business-intelligence skills and expertise in C, C++ and C# programming, temp-to-perm positions

Down: enterprise architects</comment>


Ask HN: Should I write a lean business plan for a social startup? - <AUTHOR> One of the co-founders is very big into "lean" and doesn't think any type of business plan should be written, while another co-founder believes at least some sort of light (or "lean") plan should be written. If that is the case, should the lean business plan be written as an internal compass for the founders or directed at early potential investors? <comment><USER2> yes, but it should start small and grow iteratively.

First version can be very simple: This is what we do, here is how we will make money, here is how we are going to prove that this is a viable business.

Then run some experiments (aka get your mvp product into real people's hands as quick as possible) and do some learning, and add details/change things as time goes on.

Traction beats all.

<comment><USER3> traction! so right. make something you will use as kindling and start your fire.</comment></comment>


Ask HN: What do you do when you have a lot of waiting time? - <AUTHOR>

How do founders here deal with waiting time? E.g. Waiting for a customer's reply before proceeding further, waiting for users to try out the product and give the feedback needed, etc.? Or is it even normal to have stretches of time where it <i>feels</i> like there is no work to be done? <comment><USER2> I try to have three different priority levels: (1) for things that need to get done soon, (2) for things that are worth doing but aren't so urgent and (3) things I do to improve and recover myself.

I never run out of things to do in category (2). (you can always build links, improve your toolset, work on longer-term features, try to hustle up the next customer...)

And don't forget about (3) -- sometimes the best thing you can do is go to the gym, go for a walk, or chill out playing a video game. Burnout is one of the most dangerous and insidious things, and doing things to renew yourself can really help your productivity.

To take an example, I was coding something up the other day, looking at a really old codebase I didn't understand -- I took a stab at solving the problem and I was totally baffled. I took two hours off, went to the gym, and when I came back I solved the problem in 15 minutes. If my head was in a cloud, I could have wasted days trying to figure it out.

On some level though, your question seems pretty strange to me. For my own startup, my 'management plan' involves seven different sectors -- these involve different aspects of software development, content production, marketing, etc. There are dependencies between tasks in these sectors, but there's always something that can be done. The real challenges are (i) managing my energy [not spinning my wheels, not burning out] and (ii) making sure the tasks that are critical to getting revenue in are done soon enough...

</comment><comment><USER2> Oh, one more thing, this is the exact reason I left my last job -- we were in a place where it took us a whole year to sign a customer up for a free trial... We set the system up for them in October, and they didn't even look at it until February.

I learned at this point to see long sales processes as a "bad smell." Now maybe there are some things that really take a long time to sell (Nuclear power plants, for instance.) but personally I think salespeople are the most hated people on the planet and that they're going to be first ones to go as we approach the singularity. If your product is hard to sell, you should be selling a different product.

I've seen so many enterprise products go by that cost, say $30K, and the sales process is so extensive that it costs them $15K worth of salesperson time to sell the product and it costs the customer another $30K worth of their own time to make a decision. The product is worth $15K, but sales overhead puffs up the cost to $60K to the customer.

This has just got to stop.</comment>


Reddit has launched their cryptocurrency integration - <AUTHOR> https://www.reddit.com/community-points/ <comment><USER2> Glad I deleted my account last year.</comment>


Busting IE8's Mythbusting - <AUTHOR> http://www.geektechnica.com/2009/06/busting-ie8s-mythbusting/ <comment><USER2> First: I use Chrome. IE is an awful browser. IE8 is bearable. I think that the advertising campaign that they are using for IE8 is disingenuous and despicable. As a Microsoftie, I'm not proud of it. I'm going to let it slide simply because I want as many people as possible to upgrade from IE 6 and 7. I do, however, believe there are more honest ways to go about it.

I think people have found my defensive insight into Microsoft to be a valuable perspective. Let's keep the streak going...

While the advertising teams have taken serious liberties, the engineering team has been honest.

I can't find the source now, but I've heard that they were only aiming for CSS 2 support because CSS 3 is an unfinished draft: <http://www.w3.org/Style/CSS/current-work>

Many people complained about broken standards, so Microsoft decided not to ship a browser which map to unfinished standards. This would create future compatability issues. I think that's a reasonable call considering the critical mass of their browser which causes it to be a defacto standard.

This looks to be in line with independent findings which show IE8 has fantastic CSS 2 support, but weak 3 support: <http://www.quirksmode.org/css/contents.html>

Additionally, the IE team has made significant contributions to the W3C with CSS 2.1 test cases: [http://blogs.msdn.com/ie/archive/2008/03/06/ie8-and- css-2-1-...](http://blogs.msdn.com/ie/archive/2008/03/06/ie8-and- css-2-1-testing.aspx)

<comment><USER3> I wrote this on Reddit recently:

"It's about control, which leads back up to money.

"Windows is the default OS and IE the default browser. This is also why IE is broken. Microsoft doesn't want IE to render the same as its contemporaries because then you don't need to test on IE anymore, which means you don't need Windows anymore.

"Microsoft controls things this way and it's been part of their corporate philosophy for a long time -- Embrace, Extend, Extinguish. They make something mostly compatible with the standard or competing product and then add proprietary extensions or quirks, and their marketshare alone forces people to take notice, and the hope is that eventually people will forget about the non- IE stuff and not bother to test on it anymore, meaning that now things don't work unless you have IE, meaning that you can't use the internet without Windows. That doesn't happen as often with the internet anymore, but as most of us know, it was quite successful for a pretty long time, and it's still successful for many non-web technologies (see DirectX v. OpenGL, etc.).

"And while things are no longer panning out to complete MS dominance, IE still plays a major role in defining what techs get on the web and what doesn't. For instance, crappy HTML 5 support because HTML 5 harms Silverlight. This is all intentional, don't fool yourself."

Not sure what you mean by "Microsoftie", but it'd be interesting to hear an MS advocate's or employee's position on this.

<comment><USER4> _Microsoft doesn't want IE to render the same as its contemporaries because then you don't need to test on IE anymore, which means you don't need Windows anymore._

Are you implying MS are purposely breaking IE in order to sell Windows licences to web developers? How many licenses exactly do you think are on the line here?

<comment><USER5> There's one here. I'm an Ubuntu user, but I have a paid copy of XP that I use in VMWare so I can test IE6 & 7.

EDIT: But I'm probably an outlier.

<comment><USER6> You could try out "ie4linux" (unofficial, of course) <http://www.tatanka.com.br/ies4linux/page/Main_Page>

I've heard it's nice, I think it's essential IE files and wine slapped into a pretty package - but I've also heard/seen that you can have several versions of IE for testing stuff out. Might.. be nice. I dunno.

<comment><USER5> I do also use ies4linux. It's quite good for testing how IE handles CSS layouts, but it doesn't render fonts the same way IE renders fonts on Windows (presumably because the fonts available differ on Ubuntu).

</comment></comment></comment></comment></comment></comment><comment><USER7> The IE8 comparison is very misleading. They give IE checkmarks for "security," "privacy," and "ease of use," where Firefox and Chrome get none. What, so Firefox and Chrome have ZERO security and privacy? Wow, thanks for warning me, Microsoft!

The truth is that all three browsers have security and privacy features, which are too complex to be reduced to a single checkmark. Firefox at least gives some quantified argument on its pages: "An independent study shows that, in 2006, IE users were vulnerable to online threats 78% of the time. Firefox users? Only 2%."

It's interesting that this comparison doesn't concede a single category. In "performance," they say, "hey, let's call it a tie!" Actual timed measurements of Javascript performance show that IE8 is WAY slower than the competition.

[http://www.appleinsider.com/articles/09/01/27/ie8s_javascrip...](http://www.appleinsider.com/articles/09/01/27/ie8s_javascript_performance_lags_well_behind_safari_chrome.html)

[http://service.futuremark.com/peacekeeper/browserStatistics....](http://service.futuremark.com/peacekeeper/browserStatistics.action)

Microsoft's browser comparison truly is deceptive. I'm glad they're moving people away from IE6, but they're far from having the best browser our there.

<comment><USER8> _In "performance," they say, "hey, let's call it a tie!" Actual timed measurements of Javascript performance show that IE8 is WAY slower than the competition._

Plus neither of the links you posted tested Firefox 3.5 which has improved javascript performance which implies IE8 slips further behind.

</comment></comment><comment><USER9> Complaint #1: _its_ is a possessive; _it's_ is a contraction for _it is_. (The author kept using _its_ as if it meant _it is_.)

Complaint #2: The author kept using the form:

The Lie: <a summary of the author's opinion> The Truth: <an explanation of the author's opinion>

That's messed up. The "lie" should be what he thinks Microsoft got wrong.

Complaint #3: The whole thing is just his opinions. It would be nice to link to some actual benchmark results, for example, rather than just countering Microsoft's "IE8 is the fastest" with "No it's not!"

Not worth reading.

<comment><USER7> Here's another test. Out of 10 browser versions tested, the only one that IE8 beat was IE7.

[http://service.futuremark.com/peacekeeper/browserStatistics....](http://service.futuremark.com/peacekeeper/browserStatistics.action)

<comment><USER10> That's unfair. It should be noted it also beats IE6.

<comment><USER10> But things may change as you do down the version ladder. I bet it is slower than IE 2 or 3.

</comment></comment></comment></comment><comment><USER11> As a long-time and primarily Windows user and developer, even though knowing that they're false, I was interested in seeing these so-called "facts" Microsoft has been spreading around about IE8 being busted in a clear, concise and researched way.

...But as I opened the page, this came up:

"Windows 7 is the best Windows yet (unlike Vista) and IE8 is the best IE yet (unlike IE6-7)."

Can't they be even more biased? Despite Vista having a bad launch, it was far from being a bad OS and is, as of right now, extremely solid; IE6 and 7 were a significant improvement over their predecessors.

I'm sorry to de-rail the topic.

<comment><USER12> Here's how I read that statement: IE6 and IE7 were only the "best IE yet" at release due to how truly awful each previous incarnation was. IE7 is a lousy browser, so calling it the "best IE yet" at the time was like saying that chewing on tinfoil is more fun than chewing on rusty razor blades. It might be an accurate statement, but it doesn't mean you're enjoying that tinfoil. IE8, on the other hand, actually feels like a step (admittedly a smallish step) in the right direction.

Similarly, Windows 7 is actually more _usable_ than previous Windows. Vista was shinier than XP, and had a couple nice features like integrated search, but there's a reason Dell had to start selling machines with XP licenses again.

I think the author intended the statement to be something like this: that Windows 7 and IE8 actually _deserve_ the title of "best ___ yet."

</comment></comment><comment><USER13> What this says is that Microsoft is willing to be very deceptive about a free product. But you can't blame them at all, it's just a web page. Even if this deception actually has some demonstrated effect on browser market share, those market share changes will be based on the personal decisions of people to switch. It's not like Microsoft has gone and deleted everyone's IE7 and Firefox installations without permission.

Remember that _any_ source of information should not be implicitly trusted. [Trust me! ;) ] If an individual decides to believe Microsoft's statements without doing any further research, and downloads and permanently switches to IE8 based on lies, then it's that person's problem.

</comment><comment><USER14> Lets be real here. MS's marketing lies does not make people want to use IE. There are a few major reasons why people still use IE, and all of them are marginally valid.

      Deployment tools for organizations
      That's what has always been used, why should I change?
      It's installed by default on Windows, and many users lack the knowledge that there IS something else, in addition to not knowing how to install that "something else."

The only way we can get rid of IE is to ensure that it is NOT distributed with versions of Windows, providing deployment and security lock-down tools for organizations, and educating the public about all of the options.

</comment><comment><USER15> Microsoft marketing has gone from uninspired and mildly disingenuous to outright pathetic lies.

This should come to no surprise to anyone, they feel the heat building up from multiple directions (the web slowly replacing the OS, apple gaining more and more marketshare, oss quality steadily increasing, drastic measures imposed on them by anti-monopoly organisations in the EU and many more). They face this heat, as noted by multiple commenter above, with their usual embrace/extend/extinguish tactic. Wonder if it will work on HTML5, the stakes are unusually high on that one.

</comment><comment><USER16> I'm almost starting to think that this recent IE8 promotion and "facts" is actually a clever marketing strategy.

Just releasing a poor or decent browser doesn't get that much mentions or headlines - but with outrageous claims or even lies you get tenfold mentions in blogosphere and media. It might not be a smart for Microsoft appear as liars but hey, at least people know that IE8 is out.

<comment><USER17> The media really doesn't care much for web browser competition. Blogs, do, but the blogs that care are the ones read by people who already know IE is bad.

Microsoft isn't doing some clever targeting with this. It's pretty obvious that they're going after ignorant people with an ignorant tactic, and let's face it, they couldn't attract users any other way.

<comment><USER10> For them, the best way to attract users is to make OEMs bundle only Windows+IE with computers they sell. Most people don't reinstall the OS or even know what IE is.

Targeting smart people is seldom a smart strategy - they are not as numerous.

<comment><USER17> Point. But I was talking about outside of bundling, since I figured it was a given. I'm guessing Microsoft here is trying to retain that hold, at a time when many people download Firefox or Chrome or Safari first thing on bootup.

<comment><USER10> They never engage competition on a level playfield - for them, it's a waste of resources.

Bundling makes a lot of sense because they can deal with ten, at most, clients and have a huge impact on just about every computer user on the planet. Groklaw has an interesting piece on the probable reasons why Asus pulled the plug on their ARM-based netbook and I guess this is their typical behaviour.

Want to bet the net MSN Live Messenger (or, will they call it "Bing messenger"?) will make every search on the system default to Bing?

Playing fair is so strange to their corporate DNA it would provoke a violent allergic reaction.

<comment><USER17> Microsoft is stuck in a bad place. I don't doubt they've got some brilliant people working for them, but they made a bunch of tasteless products and now they can't even scrap it all and start again because they have to offer support for all the crap they've made. So they take the only viable path, which is continuing to force crap into crap and making everybody unhappy.

<comment><USER10> Not everybody.

I won't let them ruin my day.</comment></comment></comment></comment></comment></comment></comment>


Python – our language of choice - <AUTHOR> http://blog.sunscrapers.com/post/151744005012/python-our-language-of-choice <comment><USER2> Probably Python language is the best for beginners!</comment>


Is Apple gonna generate money from its announced Services? - <AUTHOR> https://medium.com/@giacaglia/apple-services-65b5120e7e93 <comment></comment>


How to Make an SVG Lava Lamp - <AUTHOR> http://codepen.io/chrisgannon/blog/how-to-make-an-svg-lava-lamp <comment><USER2> Something very peculiar about the things this article dwells on and the things it chooses to skim. There's a lot of detail about the process of moving assets from Illustrator into an SVG file, but the clever bits seem to be almost glossed over. It literally says, for example,

"The infamous 'goo' effect is a Gaussian blur filter whose alpha contrast is boosted right up using a ColorMatrix filter (I'm not going to go into too much detail with the goo effect as it's somewhat outside the scope of this, plus it's a bit boring)."

Wait... no, I'm interested in how the gaussian blur and the colormatrix work together! How did you figure out the parameters? What other effects could this accomplish?

But apparently _that_ bit - the bit that makes this look like a lava lamp not just a picture - is _boring_?

<comment><AUTHOR> Here's further reading on the effect. I didn't include it because this combination of effects (goo) has been around for a while now and it's boring regurgitating the same explanation over and over. [http://tympanus.net/codrops/2015/03/10/creative-gooey- effect...](http://tympanus.net/codrops/2015/03/10/creative-gooey-effects/)

<comment><USER2> Well, it was new to me :) Maybe add the link to further reading into the article, then?

<comment><AUTHOR> Yes it was my bad - I've added it now. Thanks for pointing that out.

</comment></comment></comment></comment><comment><USER3> Everything looked sort of obvious except the fluidity of the goo inside. The trick used to achieve the latter is quite neat!

As far as I understand, it uses a combination of Gaussian blur, which gives the soft, fluid texture, and a clipping path which gives well-defined edges. Once two drops of goo touch, they start to visibly 'meld' due to the blur.

<comment><USER4> The clipping path was to ensure that the goo stayed inside the lava lamp -- the well-defined edges were the result of the color matrix.

You can see this easily by deleting those two parts of the pen (This is one of the great things about codepen, if it weren't for this, I would have phrased this much less confidently)

<comment><USER5> Yes, and to be perfectly clear, the color matrix is all identity except for the alpha row [0 0 0 21 -9]. This is stretching the alpha range so that many of the semi-transparent areas outside of the original blob that were generated by the gaussian blur are now completely opaque. (It's similar to a thresholding operation, but there are some middle values that survive.)

</comment></comment></comment><comment><USER6> I love SVG as a format, but don't have a lot of experience with SVG animation.

Could the animating javascript loop be redone using SVG animations?

<comment><USER4> Probably, sans some randomness. (I'd hope that any animation standard has the ability to move things up and down over time, which is the only part of this performed by the JavaScript)

My understanding is that SVG animation (SMIL) support isn't great, and it doesn't look to be getting any better.

I remember reading somewhere that even the browsers that do support it don't like it, for whatever reason (but I could be wrong about this, I'm having trouble finding where I read that again, and only vaguely remember it in the first place)

<comment><USER7> Chrome is depreciating SMIL [https://groups.google.com/a/chromium.org/forum/#!topic/blink...](https://groups.google.com/a/chromium.org/forum/#!topic/blink- dev/5o0yiO440LM)

<comment><USER8> OTOH CSS animations still remain so it can still work for embedded .svg files. source: your link

</comment></comment></comment></comment><comment><USER8> Really nice. I would add an animating affine transform for the goo blobs so when they approach the top they get narrower and longer. This way the individual blobs would constantly change shape too making it a little bit more "gooey".

<comment><AUTHOR> There are lots of things I would add to this (and your suggestion is one of them) but I wanted it to run on mobile too - therefore I had to 'feature-cut' where I thought it would have the least visual impact.

</comment></comment><comment><USER9> This is really nicely done. I love the lava lamp animation bit in addition it's accompanied by a good write up. Well done sir!

<comment><AUTHOR> Thanks!

</comment></comment><comment><USER10> Does not work in Firefox. :(

<comment><USER11> It works fine under Chrome, and Safari (both in OS X).

<comment><USER10> Aye, works in IE11 too. Just not Firefox.

<comment><AUTHOR> What exactly isn't working about it in FF? Blobs not moving? No blobs at all? No graphics showing at all?

<comment><USER12> I am seeing blank space. FF41 on Windows 10.

<comment><AUTHOR> Are you looking at this [http://codepen.io/chrisgannon/pen/QjKXXe](http://codepen.io/chrisgannon/pen/QjKXXe) ?

<comment><USER12> Still only seeing a blank screen. I have checked with both ABP enabled and disabled. It must be one of my extensions. I will test later and inform you.

</comment></comment></comment></comment></comment></comment></comment><comment><AUTHOR> Thanks all for testing this on the all the different platforms. Slightly annoyed to hear FireFox is playing up given I've tested it there and it worked for (both Mac and Win 10).

</comment><comment><USER13> The whole lamp is nowhere to be seen in the whole article or have I missed something?

<comment><USER14> Yes it's in the break above the paragraph above "Stop Jabbering". It's an embedded codepen.

</comment></comment><comment><USER15> Gotta love that Gaussian blur filter.</comment>


What makes a joke funny? - <AUTHOR> https://www.bostonglobe.com/ideas/2018/12/13/say-cuckoo-not-bird-how-computer-models-can-help-stand-comics/AKHtmpf9StBCMyN3B6XB9O/story.html <comment><USER2> The probability of a joke being funny increases as a function of attraction as well</comment>


How is LLVM tested? - <AUTHOR> http://lowlevelbits.org/system-under-test-llvm/ <comment><USER2> "Amount of unit tests is pretty small comparing to regression tests. One reason behind that decision is that LLVM internals constantly change all the time. "

Well, no, and i'm not sure where they got this. It's not a "decision". BTW, This also assumes that all of the tests in the unit test dir are unit tests, and all the tests in test/ are regression tests.

This is explicitly false.

The general viewpoint of LLVM is that most things people write (analysis, optimization) should be tested by checking the IR or dumps. That is, we want easy to follow and modify unit tests, not just compilable C++ code ones.

Thus, you will find a lot of unit tests that are in test/, instead of unittest/, because they are testable using IR printers.

Those things that are API's should be tested by unittests, and work is underway to increase coverage. The reason some things aren't cover is simply that in the earlier days of the project, not all of this got unit tests, and it's only in the past couple years that people have become sticklers about it.

So that one would be knowingly "not enforcing good development practices", not "llvm internals change all the time". The fact that internals change all the time is in fact a _good_ reason to _have_ unit tests.

<comment><USER3> The lit test are not really "unitests" per-se, even if we try to consider them as it. We are writing them to stress a specific part of the compiler (can we vectorize this specific construct for instance), but they still involve a large chunk of the compiler. The reason we don't have more real unittests is IMO because: \- it is hard to write (you need to mockup the analysis result that is used by the vectorizer if you want to test it in isolation). \- it adds lot of maintenance burden/overhead \- it does not add much value for the compiler over the lit tests.

<comment><USER2> "The reason we don't have more real unittests is IMO because: - it is hard to write (you need to mockup the analysis result that is used by the vectorizer if you want to test it in isolation)"

Right, and it's infinitely easier to just dump the result of the analysis and check that it said what you want using lit.

We even have a framework explicitly to do that -analyze for opt is specifically meant to run analysis and dump their output.

This doesn't test API boundaries, but the dumpers and printers are usually forced to be written in terms of the API.

(and folks are starting to get religion about testing the other API boundaries)

</comment></comment></comment><comment><USER4> If you're interested in the testing techniques used by established open source software, here are a couple projects that appear to have far more extensive test coverage than LLVM:

SQLite ( [https://sqlite.org/testing.html](https://sqlite.org/testing.html) )

Opus ( [https://www.ietf.org/proceedings/82/slides/codec-4.pdf](https://www.ietf.org/proceedings/82/slides/codec-4.pdf) )

I don't mean it as criticism of the LLVM project, as I haven't worked with it and can't say whether its tests are sufficient. Only that, from reading this overview, its testing techniques do not seem particularly elaborate.

<comment><USER5> Thanks too.

Opus testing is impressive:

> Run thousands of hours of audio through the codec with many settings

\- Can run the codec _6400x_ real time

\- 7 days of computation is _122 years of audio_

</comment></comment><comment><USER6> Very nice. Anyone could point me to LLVM's code coverage and whether they use TDD?

"Amount of unit tests is pretty small comparing to regression tests. One reason behind that decision is that LLVM internals constantly change all the time. Supporting tests under such conditions is very time consuming."

Isn't the whole promise of testing is easier maintenance in the long run? Also, regression tests seem to run much faster, is it because of the Google Test?

<comment><USER7> Yes, but if you're not wise about _how_ you test it's easy to not get the bang for your buck. Cargo cult testing is a very real problem.

Example: I was extending some code the other day that had 3kloc of thin wrapper code and 30kloc of mocks and unit tests which effectively did nothing but ensure that the 3kloc passed things through unaltered. Meanwhile, the code is widely acknowledged to be frustrating to interface with because it uses a string-based API that isn't documented (and no, those unit tests won't tell you semantics), versioned, or maintained with an eye towards compatibility. Naturally, there are no integration tests with the layer above or below it, and those interfaces are where all the actual bugs happen. So the tests increased cost by a factor of 1000% and had 0 return.

Also see: cargo cult comments. You know, these guys:

        /**
         * Gets the foo.
         */
        Foo getFoo() {return foo;}

Anyway, my personal rule of thumb is to start with integration tests and only drop to the granularity of unit tests if I've got a "logic hairball" on my hands where the interfaces are much simpler than the internal logic (parsing and algorithm implementations, usually). I'd be happy to hear other opinions though!

<comment><USER8> My experience with integration tests first is that a handful of use cases get stuffed into these test cases, but it's harder to figure out what you are actually testing. It's good to test that everything comes together and works in this one cherry picked case, but I'd rather be able to give the more granular guarantee that all of my components hold up their individual contracts.

<comment><USER9> Doesn't it make sense to focus on contracts at a higher level of abstraction though? Wouldn't it be better to put the contracts at the level of the user rather than setting contracts for most/all of the functions in your code? If the mocked user input resulted in the correct output and there were no other side effects, wouldn't that be sufficient in many cases?

<comment><USER8> There might be confusion about terminology here. I think of unit tests as testing contracts of individual units and then each appropriate level of abstraction has its own set of unit tests. Integration tests are those that use the external user interface and represent a use case, BUT a unit test of layer N+1 could effectively be an integration test of layer N (I just wouldn't call it that if it was using a mocked layer N interface).

<comment><USER10> > ... BUT a unit test of layer N+1 could effectively be an integration test of > layer N (I just wouldn't call it that if it was using a mocked layer N > interface).

Fixing the problem of unit tests becoming de-facto integration tests is exactly what mocks are for. If you don't mock your dependencies, then you are in fact executing an integration test. The problem becomes that your mocked dependency and the real dependency can now drift because there's nothing tying them together. So a unit test works but you still have an integration bug.

Personally, I think both unit and integration tests are really important, but that integration tests tend to get a bit underlooked with all the existent zeal towards unit tests. Testing a component's contract is obviously necessary, but testing that your components are expecting the correct contract from others is also important.

<comment><USER8> I agree, both are really important. I think integration tests get passed over because they require a higher level view of your software. Personally, in my day job, I'm not extremely familiar with the domain, so I'm pretty ineffective at writing sensible integration tests. I can, however, pass my unit tests/contracts off to the guys that are familiar with the domain so they can shape up an integration test.

</comment></comment></comment></comment></comment></comment></comment><comment><USER11> Very interesting article, thanks!</comment>


Ask HN: Any open-source webapp RSS reader? - <AUTHOR>

Anything that can match the reading experience of feedly.com. <comment><USER2> I'm not sure about feedly's reading experience. But I liked miniflux[0] when I used it. It's likely not as fancy as feedly.

0\. [https://github.com/miniflux/miniflux](https://github.com/miniflux/miniflux)</comment>


London Underground Wifi Tracking:  Everything We Learned from TfL's Report - <AUTHOR> http://www.gizmodo.co.uk/2017/09/london-underground-wifi-tracking-heres-everything-we-learned-from-tfls-official-report/ <comment><AUTHOR> One thing the article doesn't really mention is the accessibility (or lack of) for some of the stations.

Some people want to avoid stairs, or avoid long walks.

Here's the section of the map they're talking about: [https://pbs.twimg.com/media/DJRaXWHXUAAD05q.jpg](https://pbs.twimg.com/media/DJRaXWHXUAAD05q.jpg)</comment>


Great platform for hosting Node.js and MongoDB - <AUTHOR> https://www.nodechef.com/nodejs-mongodb-hosting <comment><AUTHOR> NodeChef provides a great platform for developers who don't want to wrangle with the complexities of server-side infrastructure or using multiple services to host an app. By Integrating both the database and the app server into a single cloud service, developers are able to effortlessly host their applications.</comment>


Majestic-12 Distributed Search Engine - <AUTHOR> http://www.majestic12.co.uk/ <comment><USER2> That is interesting, but it says :As of 5 July 2014 Project continued for existing members only, also I cannot find any source code.

Take a look at yacy.net, it is free software and is very good.</comment>


There's an easy way to tell if you're talking to an expert or a faker - <AUTHOR> http://www.businessinsider.in/Theres-an-easy-way-to-tell-if-youre-talking-to-an-expert-or-a-faker/articleshow/53948739.cms <comment><USER2> > I'm clearly not an expert in expertise - just look at the hubris and > overconfidence dripping from this article!

The article meta-invalidates itself. :D

</comment><comment><USER3> This is clearly clickbait; the article is full of links to other 'seemingly related' articles used as 'examples' of the very thin point the guys is waving around. Oh and add a bit of climate change thing as a bit of icing.

Pretty much a textbook example. And I'm an expert!</comment>


Algorithmic Web Design - <AUTHOR> http://hery.ratsimihah.com/2013/05/15/algorithmicdesign.html

<comment> 97-109-107 >Can web design generated algorithmically still be considered creative and artistic?

what I think you really mean is:

>Could algorithmically generated web design possibly maintain an acceptable level of usability?

Because 'creative' and especially 'artistic' imply websites which are medium of artistic expression, which I doubt is ever subject of our discussion here at HN. (ex. Olia Lialinas <http://rhizome.org/artbase/artwork/1729/>)

To which I think the answer is yes; but right now would require a human to assign importance/context of elements of a websites, before generating specific styling to particular element groups (as in: body, footer, menu, etc.). There is some subtle evidence in the generative art field, that there can exists aesthetic results to 'just' an algorithm. The next question you want to ask is - how narrow do we need to define the algorithms to make it a workable approach? With genetic algorithms on the run, thinks seem to be improving.</comment>


Sketch is 50% off today - <AUTHOR> https://itunes.apple.com/us/app/sketch/id402476602?ls=1&mt=12

<comment><USER2> I am confused by this app. It has two templates both of which are for icon design, and it has handy dandy guides for a main icon area. How do you get duplicates of whatever is in the main icon area in all the little side areas? Or is this really a bit of gimmickry and nobody really uses this program to make icons?</comment>


Guy writes Common Lisp library to machine-tool casings for MIDI controllers - <AUTHOR> http://ruinwesen.com/blog?id=387

<comment><USER2> It's interesting, but I wonder why he didn't just buy SheetCam for $150.

<http://www.sheetcam.com/Features/Milling.shtml></comment>


A feeless payment, bank-bank, without having to know your account number - <AUTHOR>

I've been working on a system to make and take payments directly bank to bank with no fees and without having to know your bank number for a while, and we've finally got it pretty darn fast.
This isn't quite a launch announcement, hence the time of day and nature of this post, but if anyone wants to be really helpful, check out this quick video of me making a live payment I made and let me know what you think! I would and always do appreciate it.
https://www.youtube.com/watch?v=QR5UTLxe5zA&feature=youtu.be <comment><USER2> We have this thing up in Canada called Interac Online - you may find it of some use/inspiration as you build out yours...I believe the tx fees are flat rate vs %age...

[http://www.interac.ca/index.php/en/interac-online/interac- on...](http://www.interac.ca/index.php/en/interac-online/interac-online-for- consumers)

<comment><AUTHOR> Thanks! Checking it out.

</comment></comment><comment><USER3> Standardized payment tickets that can be used to pay rent, utility bills, personal payments, etc. have been in use in Brazil since the 1980's.

In the system they have over there any person can print out a sort of invoice that can be paid in cash at the teller window at any bank or at an ATM or your own bank's website. It's useful since people often don't have bank accounts but need to pay bills. All the banks are on this network and any bill issued by any bank can be paid at the teller window for any other bank.

Look up "brazil boleto bancario" if you want to research how it's done. The system isn't perfect, but it's quite serviceable and commerce in that country would grind to a halt if it stopped working. Nobody uses checks to pay for things like credit card bills, utility bills, rent, etc.

</comment><comment><USER4> How does it work? I'd guess you're logging into the user's bank on his behalf and initiating a transfer? What are the security and legal implications? Am I expected to trust a 3rd party to have complete unrestricted access to my bank account?

<comment><AUTHOR> We act like and have the same compliance standards as a bank - so we don't have "unrestricted access" to your bank account anymore than someone you give a check to does. Yes, that person now has your bank account and routing number (because it's printed on the bottom of every check you've ever given anyone), but they only can legally do what you authorized them to do: cash that check for that amount. We're the same way.

The only additional thing you give us is temporary access to some other information in case you want to transfer it (name, address, etc) - but we don't store it. We also have access to your payment history temporarily to ensure that you're likely to

1\. Be who you say you are (fraud protection) 2\. Have the money to make the payment.

But both of those things are just temporary - we don't and can't store it and we don't and can't use it for anything other than explicitly what it's for.

Side note: government gets a lot of hate in the Tech community, but this is a place where regulation is fantastic. Since we have to be Regulation E compliant, even if someone (investors, partners, etc.) wanted us to use this access for bad purposes, we can't! You're protected and therefore we're protected. As the founders of this company, we wouldn't WANT to nor would we ever do anything with your information, but it's fantastic not to be under any pressure to do so.

<comment><AUTHOR> "Temporary" means "while you're making the payment". Once that's done, it's gone. It's never stored outside of the memory, so we couldn't keep it longer if we wanted to.

</comment></comment></comment><comment><AUTHOR> Clickable

[https://www.youtube.com/watch?v=QR5UTLxe5zA&feature=youtu.be](https://www.youtube.com/watch?v=QR5UTLxe5zA&feature=youtu.be)

</comment><comment><USER5> I think it's pretty cool, How will you guys monetize? and are there any other use cases for it?

<comment><AUTHOR> Hey thanks! Subscription - so instead of paying a fee on a payment, you pay a small subscription based on how many payments you take a month. We're designing to take care of lots of edge cases (to allow more micro-transactions than CC's can realistically permit) and ensure it's always an 85-99% reduction on what fees would have cost you.</comment></comment>


Is there any software to help me manage my CV? - <AUTHOR> I'm actively searching for a job. The problem is, I worked (and still working) in multi-disciplined roles.
The work I do can be titled as a data scientist, AI engineer, ML engineer, and backend engineer. So naturally, when I tailor my CV to apply for a new job, I want to include only the relevant skills and projects, and describe the relevant work I did in my previous roles.
It became very tedious to manage my 10+ CV templates!
So my question is: is there any software or website that helps me manage many versions of my CV easily? Ideally it will help me easily add/remove skills, projects and certificates. It will also be useful if it can handle multi descriptions of previous roles!
P.S. if such a thing doesn't exist, I'm gonna create it. I'm THAT fed up with this problem. <comment><USER2> I use a basic JSON data structure with some Go code that reads it, filters on various things (primarily date ranges at the moment), and outputs it via a template to HTML.

For multi descriptions, I'd change the description key from a string to a hash and then have an option to select those of a particular "flavour".

Something like:

        d: {"ml":"I made funny carrot names with ML", "data":"Extensive processing of botanical nomenclature", "mba":"Some guff about something business processes"}

And then something like:

        ./gencv -flavour ml > ml.html # uses ml.tmpl
        ./gencv -flavour data > data.html # uses data.tmpl
        #etcetcetc

You could even lash it up in shell with `jq` and `sed`...

<comment><AUTHOR> Nice! any plans to opensource your code :) ?

<comment><USER2> Oh, I can do but I promise you that it's rough as a badger's arse because it was a quick lash up. I'll see if I can throw it up somewhere later today.

</comment></comment></comment><comment><USER3> if ever you already know LaTeX, you can use the simple programming constructs (if/then/else) to generate different CVs by switching flags

actually, in Linux, I used file links (multiple filename pointing to the same file content) to active different booleanflags, eg cv-paper.tex, cv- anonymous.tex, ...

<comment><AUTHOR> Seems like a nice idea, but still looks like a lot of manual work..</comment></comment>


Live Longer: The One Anti-Aging Trick That Works  - <AUTHOR> http://news.yahoo.com/s/livescience/20080708/sc_livescience/livelongertheoneantiagingtrickthatworks

<comment><USER2> Caloric restriction is the only non-genetic intervention proven to increase maximal lifespan in mammals. However it may well be that the magnitude of this effect in humans is considerably smaller than in lower mammals because the mechanisms that repair the damage that accumulates as a consequence of normal metabolism are already more optimal. I think the really interesting area is caloric restriction mimetics. These are alluded to in the article and are a class of small molecule compounds that aim to induce the life-extending effect of CR without the need for reducing calories. GSK recently made a 0.75 billion dollar investment in Sirtris pharmaceuticals <http://www.sirtrispharma.com/pipeline-candidates.html> who are developing a reversatrol derivative so this is far from science fiction.

</comment><comment><USER3> I think exercise has also been shown to work.

<comment><USER4> Not really, as your organs would still have to work to process the extra calories. The fewer calories you process the less wear and tear in your organs.

And if you eat a sandwich after running for an hour you're breaking even calorie-wise, so exercise isn't even so efficient.

<comment><USER5> Not true because a) within reason, using any of the body's systems makes them _stronger_. That's the _point_ of exercising. And b) effective exercise isn't about burning calories directly, it's about raising your resting metabolic rate.

<comment><USER6> I've heard it suggested though that the extra calories cause your cells to divide more frequently, which means you run out of telomeres faster. Not sure if that's really true or not though.

</comment></comment></comment></comment><comment><USER7> Eat less? You don't live longer; it just _seems_ longer.

<comment><USER4> Your stomach shrinks when you eat less. You can live comfortably and energetically from 1800-2000 kcal per day. Less if you sit on a chair all day.

Bonus: you save money.

</comment></comment><comment><USER8> Where are we, on digg.com?! The subject line of this post should have said "eat less" in it. I shouldn't have to go to the article to get those two words.

</comment><comment><USER9> I misparsed the headline to say that the way to avoid looking older is just to live longer, to have a slower metabolism.

<comment><USER10> I even thought of they meant a tautology: Living longer makes you live longer.

</comment></comment><comment><USER11> Now if there was only a pill that took hunger away, so that you could eat the allotted amount and no more...

<comment><USER12> Those pills are out there, in varying shades of legality.

Dexatrim comes to mind. (As does any Pseudoephedrine carrying drug)

<comment><USER11> Which one is the most legal/safest?

<comment><USER13> Probably Sudafed, or any generic version of it. It's one of the few medications you can safely take while pregnant. That said, the long term effects of any metabolism boosting substance on the heart, etc., are probably not great.

The best thing for the less food-disciplined may be to follow the NoS plan ( <http://www.nosdiet.com/> ).

<comment><USER12> Sudafed no longer uses pseudoephedrine in its products because it was being used to synthesize meth. It now uses phenylephrine, which does not have an appetite suppressing effect.

I only happen to know about pseudoephedrine's appetite suppressing side effect because of terrible allergies. For years I hated eating, until medications stopped including it as the active ingredient.

<comment><USER13> You can get the "old formula," in most states, but they keep it behind the counter and you need to hand over your driver's license to be scanned. I only happen to know that because the phenylephrine doesn't work anywhere near as well for me when I have a cold.

<comment><USER12> Yeah, the phenylephrine is garbage. I just ended up stopping taking anything and got a prescription for one of those nose sprays.

</comment></comment></comment></comment></comment></comment></comment><comment><USER14> It's not how long you live that matters, it's whether you enjoy life.

I'd rather live to 50 and have a wonderful life, than life to 100 and be less happy.

<comment><USER15> Live a happy life till 50 Or live a happy life till 100? Which one would you prefer now?

<comment><USER16> After reading that article, I'd prefer a hamburger.

</comment></comment></comment><comment><USER17> Churchill lived for 90 years fat as a pig and smoking like a crack whore.

I call bullshit and a way to cut food production in half by persuading everybody to eat less.

Stress kills, food doesn't.</comment>