Russian Physicists Solve Radio Black-Out Problem for Re-Entering Spacecraft - <AUTHOR> http://www.technologyreview.com/blog/arxiv/26222/ <comment><USER2> Trivia: the space shuttle avoids the blackout by its shape, which allows it to communicate _upward_ to the TDRSS satellites.

[http://en.wikipedia.org/wiki/Communications_blackout#Reentry...](http://en.wikipedia.org/wiki/Communications_blackout#Reentry_communications_blackouts)

"[T]he Shuttle can communicate with a Tracking and Data Relay Satellite during re-entry. This is because the shape of the Shuttle creates a "hole" in the ionized air envelope, at the tail end of the craft, through which it can communicate upwards to a satellite in orbit and thence to a ground station."

<comment><USER3> I sincerely thank you, it's something I've always wondered about but never put in the time to actually look it up.

</comment></comment><comment><USER4> One thing they did not mention is that this solves the primary problem with orbital crowbars (fictionally called "Rods from God", "Thor", KEWs, and various other things). You could drop a kinetic warhead (basically a crowbar) from orbit to kill a tank / bunker / whatever, but you could also use them for a variety of peactime missions such as mining, emergency flood control (digging drainage ditches, causing controlled landslides), etc.

Each crowbar would need some sort of minimal steering system to account for atmospheric turbulence. This steering can't be locally controlled because the device can't see past the plasma sheath. It can't be remote controlled because the plasma sheath stops transmissions. With this new "plasma aerial" technology, you could steer each crowbar individually from the launcher platform.

<comment><USER5> interesting! what kind of materials need to be used so that crowbar doesn't burn-up on reentry? isn't it a little bit more expensive than using traditional explosives?

<comment><USER4> If you made it out of steel, it would survive just fine -- there would be some ablation, but it would still get to the ground.

As to the "more expensive"...no, not really. Basically, it's just a crowbar with a simple camera and some fins on it. Using this technology it would trade in the camera for a radio back to the launch vehicle. You'd need all the same bits on a missile, plus more besides, and the missile would need to be larger.

<comment><USER5> yes, but you don't need a missile to build a dam :)

sure, it will be less expensive to kill a lot of people with this. those are not cost savings I had in mind.

</comment></comment></comment></comment><comment><USER6> That should read _Theoretically Solve_ but I admire the ingenuity nonetheless and hope that the road from theory to practice is short and uneventful.

A shame this hack has military applications, it would be nice if every now and again scientists patented their discoveries and precluded military use in doing so. [ Please don't downvote me for expressing this sentiment :) ]

<comment><USER7> I thought there was a clause making all technology available for national defence, regardless of patents... but can't find the source. Anyone?

<comment><USER6> That may be true in the US but what about in other jurisdictions? I mean doctor's have the Hippocrates oath of do no harm to the patient but (and not to come over all tree-hugging peacenik like) why do chemists/bioengineers/physicists not have a similar oath with respect to the our species or other species in general or the planet in its entirety? But I guess the scientists do the theorizing and the engineers and coders build weaponize or apply the theoretical results in military applications so what good would it do ... Hmm, maybe the New Year is making me come over all compassionate and fuzzy :)

<comment><USER8> In Canada, there is a Ritual Calling of the Engineer, which has an "Obligation" which is not exactly an oath. [http://en.wikipedia.org/wiki/The_Ritual_of_the_Calling_of_an...](http://en.wikipedia.org/wiki/The_Ritual_of_the_Calling_of_an_Engineer) I'll paste the text here if I can find it.

<comment><USER9> It's a beautiful tradition. On my graduation all soon-to-be engineer colleagues also made a solemn promise more or less like the ones other engineers take in other countries and schools.

I also like the idea of passing the iron rings down through generations of new engineers. In Brazil we don't. It reminds the ones new to the career that others came before them and that others will come after them and of the obligations we share. That's one thing many of us forget much too frequently.

<comment><USER8> In Canada, I've heard it's more "traditional" to let the newer engineers wear shinier rings, so the more experienced ones have tarnished rings. One of the older engineers lost his in some machinery and had to get a new one. He hated it, said it made him feel like a n00b :-)

</comment></comment></comment></comment></comment></comment><comment><USER10> It reminds me of the Navy's sea water antenna system ([http://www.public.navy.mil/spawar/Pacific/TechTransfer/Produ...](http://www.public.navy.mil/spawar/Pacific/TechTransfer/ProductsServices/Pages/SeaWaterAntennaSystem.aspx)).

I know nothing about this thing, but I would have thought the plasma would be on the underside of the craft, allowing any antennae on the top to communicate with a satellite that could relay everything to/from the ground station.

<comment><USER11> Wouldn't the plasma flow around the craft from bottom to top like a bubble?

<comment><USER12> Yeah, it does.

</comment></comment></comment><comment><USER13> I stumbled onto this a while ago: <http://en.wikipedia.org/wiki/Plasma_antenna>

</comment><comment><USER14> Anyone else see a weird font used for double-F's?

<http://i.imgur.com/EpolQ.png>

<comment><USER15> The document uses a ligature ( <http://www.fileformat.info/info/unicode/char/fb00/index.htm> ) for ff. Apparently the font your browser uses by default doesn't have it. Some font replacement algorithm decided that the script font you're seeing is the closest! :-)

</comment></comment><comment><USER16> This might be a completely dumb idea and it must've been explored before, but how about attaching the antenna to a string and trailing it behind the ship at a considerable distance to clear the extent of the plasma shield. Is it that no string is strong or plasma-resistant enough?

<comment><USER17> When re-entering, spacecraft are being decelerated, so anything towed behind the spacecraft will catch up with it. A rigid pole might work.

<comment><USER4> They mention this in the article, where they talk about extending an aerial out past the plasma sheath. They then say "this allows communication until the aerial ablates."

</comment></comment></comment><comment><USER18> One thing that has always seemed to rub me wrong in space exploration is the giant need to stay in touch with Earth. Supposedly the space shuttles are crewed by the great explorers of our time, but it always seems that everything is governed by people on the ground and not in the air.

<comment><USER19> Basically it's resource management, both human and materials. I'll leave the human side out, but recommend Gene Kranz book _Failure Is Not an Option_ for more info on why ground controllers are important.

It costs a huge amount of money (in fuel) to lift anything up, even just a kilo or two. You're better off lifting only a telemetry system and putting all the processing, display and engineering on the ground. That means having ground controllers to manage it.

Of course, in the early days, you couldn't physically fit computers in the capsule. Now we can, but it is still more economical to have most of it on the ground and just use radio to let the systems communicate.</comment></comment>


Ask HN: Machine Learning, Where to Start? - <AUTHOR> Am just Starting ML. Have extensively worked on Vision Algorithms. Got few pointers (Andrew NG course, Tensor flow etc) to start. Appreciate if you can guide me the best way to start learning concepts and implement ML from Scratch. <comment><USER2> The advice you've been given so far is sound. Do the Andrew Ng Coursera course. It will give you a great introduction to key areas of machine learning. Andrew Ng is a terrific educator.

The level is pitched just right - enough maths to understand what's going on and implement it yourself - but not so much that it detracts from the key focus of the course.

The exercises give you a great opportunity to actually implement the algorithms covered and really aid understanding.</comment>


Apple Reports Q4 Results, $108B in annual revenue, $26B in earnings - <AUTHOR> http://www.apple.com/pr/library/2011/10/18Apple-Reports-Fourth-Quarter-Results.html

<comment><USER2> To me, the biggest news here is the 1QFY12 guidance of $37 billion. Guidance of 30% above their best recorded quarter ever. Wow.

<comment><USER3> Yes, a monster guidance. And remember this is Apple's estimate, which is has always been a lowball recently (even for this quarter, which was a little disappointing). $40B is definitely possible.

Certainly the iPhone sales this quarter weren't that great, but given the circumstances (most people knew the 4s/5 was coming), as well the 4s sold 4 million units on its opening weekend (almost 1/4th of all of last quarter's sales), I don't think it was that bad at all.

Obvious disclaimer: long AAPL, may buy more tomorrow

<comment><USER4> Lowballing quarterly earnings seems to have been a Jobs thing. With Cook on the saddle I'm guessing this will be the pattern going forward.

</comment></comment></comment><comment><USER5> The headline could plausibly, and amusingly, be: "Apple Disappoints With 52% Year Over Year Profit Growth"

<comment><USER6> Note that apple, which has >50% YoY growth, is trading about about 16.5 P/E (ttm). Stock dropped about 6% after hours. As a point of reference, Yahoo also announced results ( revenues down 5% YoY), has a P/E of 17.5, and it's stock ROSE after-hours. Boggles the mind.

<comment><USER7> I'm not convinced the stock shift is fully explained by "missed estimates" as you notice here. The highest open interest was piled into the ~390 puts for most of the day and look where the stock wound up. This is relevant because the monthly options all expire on Friday. Earnings hasn't happened before options expiration in a while so there could be a lot of institutional play in the market to zero in a particular price to prevent options exposure in both calls/puts. Keep in mind only 0.95% of AAPL stock is owned by individuals[1].

[1] Checked holdings on a Bloomberg earlier out of curiosity.

EDIT: Some related theory:

[http://www.aaplpain.com/Site/Home/Entries/2011/10/18_Apple_O...](http://www.aaplpain.com/Site/Home/Entries/2011/10/18_Apple_Option_Pain__Step_1__Acceptance.html)

</comment></comment></comment><comment><USER8> Apple missed streets expectations. Please sell your stocks... so I can buy :)

</comment><comment><USER9> Anything Apple does these days always disappoint analysts. Well, most analysts are overpaid for what they do anyway.

Financial Analysts has been underestimating Apple since 2004. This time they're pumping up the expectations.

Overall it is still a spectacular Quarter for Apple.

<comment><USER10> I just read about how the stock tumbled because the results were less than expected.

"Highest September Quarter Revenue and Earnings Ever" and it's a disappointment.

This is like the market equivalent of "eh, her knees are too pointy".

Scumbag stock market. Why not forget IPOs and stay private?

<comment><USER11> The reason the stock fell is because the expected results were built into the price. So when the numbers didn't meet the market's expectations, the price adjusted accordingly.

The expectations have nothing to do with where they were last year. Rather, they're built on forecasts of how the market (and Apple) think they _will_ do in the future.

<comment><USER10> As already mentioned in this thread, expectations of how it WILL do for this quarter are astronomical. Sales numbers that are already in back this up.

Also see here: <http://news.ycombinator.com/item?id=3128143>

So, no, this shift is _not_ explained by how anyone thinks Apple will do in the near future.

<comment><USER11> Good link. I'm not sophisticated enough to consider those aspects. I was really only referring to the spectre of beating YoY numbers by %50, and it still being considered "below expectations"

</comment></comment></comment></comment></comment><comment><USER12> I am curious if the expectations had taken into account the slipped release. There is probably no doubt the slipped release hurt them, but typically, the new iPhone comes out June/July and probably fuels a large portion of their Q4. With the 4S just coming out, it will fuel their Q1 instead.

Additionally, if they did try to account for the late release, they probably had more people than expected holding off for the new phone. That could prove beneficial in Q1. Most of the articles call out that the dip in expectations will likely be short lived, pointing to the sales in the first days of the release.

</comment><comment><USER13> The price seems to be dropping. $422.24 at close today and $393.74 after hours (@3pm pacific 10/18/2011)...

[http://www.google.com/finance?client=ob&q=NASDAQ:AAPL](http://www.google.com/finance?client=ob&q=NASDAQ:AAPL)

<comment><USER14> Analyst expectations missed. <http://www.cnbc.com/id/44908357> Seems likely due to iPhone 4S shipping later than their normal cycle? That'd also be why guidance for the next quarter is so high I imagine?

<comment><USER15> Apple always lowballs guidance (note Apple beat its own guidance by about 2B I believe) so its up to the street to set their own view of what Apple should be making (on top of Apple's estimations). Of course they're just guessing based on past results so its way less accurate.

Its a bit of Apple's fault however. They're noted for low balling revenue guidance which is why the street likes to tack a few billion on whatever Apple says.

</comment></comment></comment><comment><USER16> Gross margin was down 1.5% over last quarter. Anyone want to guess what lower margin products they sold more of?

I'd guess Macbook Airs, but there are certainly other contenders.

<comment><USER17> You don't compare numbers against the previous quarter, you compare numbers against the same quarter, the previous year.

Apple's gross margin this quarter was 40.3 percent, compared to 36.9 percent in the year-ago quarter

<comment><USER16> That's true of revenue, but as far as I know there's not as much annual cyclicity for margins.

<comment><USER18> I don't know much about consumer product sales, but I wouldn't think that it's entirely impossible that different products have somewhat different seasonal sales patterns.

<comment><USER19> People buy lots of laptops in August/September for back to school. People buy lots of iPods in December for gifts. People buy lots of iPhones in whatever quarter they launch a new iPhone in.

</comment></comment></comment></comment></comment><comment><USER20> I only have two words to say: Truly staggering.</comment>


Pillow-SIMD – Fast, production-ready image resize for x86 - <AUTHOR> https://blog.uploadcare.com/the-fastest-production-ready-image-resize-out-there-part-0-7c974d520ad9 <comment><USER2> Is doing lanczos really faster and/or better quality for scaling down than just doing a simple pixel mixing:

[http://entropymine.com/imageworsener/pixelmixing/](http://entropymine.com/imageworsener/pixelmixing/)

I implemented this for my image pipeline:

[https://github.com/pedrocr/rawloader/blob/230432a403a9febb5e...](https://github.com/pedrocr/rawloader/blob/230432a403a9febb5e5c004780211f7e765130b9/src/imageops/demosaic.rs#L155-L190)

Makes for simple enough code and even before any serious effort at optimization or SIMD it can convert a 3680x2456x4 image in 32bit float (source article is 3x8bit) to 320x200x4 also in 32bit float in about 60ms (across 4 threads in 2 cores on a i5-6200U).

<comment><USER3> Probably not faster. Definitely better quality. As Alvy Ray Smith said, a pixel is not a little square, [http://alvyray.com/Memos/CG/Microsoft/6_pixel.pdf](http://alvyray.com/Memos/CG/Microsoft/6_pixel.pdf)

Edit: If you want to do even better than the tensor product Lanczos filtering, you can do a filter based on Euclidean distance. Make sure that you work in linear (non-gamma-adjusted) color space.

A couple more resources to read: [http://www.imagemagick.org/Usage/filter/#cylindrical](http://www.imagemagick.org/Usage/filter/#cylindrical) [http://www.imagemagick.org/Usage/filter/nicolas/](http://www.imagemagick.org/Usage/filter/nicolas/)

Edit 2: really weird that this is getting downvoted. There's not really anything to dispute here. It is straight-forward to show that the Lanczos method has objectively better output. Moreover, Alvy Ray Smith's paper is a classic which anyone interested in image processing should read.

<comment><USER4> That memo needs to die. There are better ways to make the few of its points that are still valid, without making assumptions and assertions that are frequently invalid with today's technology.

Pixels are often not representative of little squares (rectangles). However, they are more likely to be representative of little rectangles now than they were in 1995, now that most photographs are captured on Bayer arrays of square sensors, most computer-generated images are rendered as an average of point samples weighted according to estimated coverage of a square pixel, and everything is displayed on LCD or OLED panels with square pixels comprised of rectangular subpixels. If you take a random JPEG or PNG off the Internet, interpreting the pixel data as point samples will usually be less accurate than interpreting them as integrated over a rectangle. Interpreting the data as integrated over a gaussian distribution is also less realistic than the rectangle interpretation. Doing image processing in a point sample or gaussian context is certainly useful, but it's definitely not more fundamentally right than the little square model. Historically, that context was at best a neutral choice that was equally unrealistic no matter what kind of hardware you were working with, but mathematically convenient.

The paper's arguments about coordinate systems (whether the y-coordinate should grow toward the top of the screen or the bottom, and whether pixels should be centered on half-integer points) are also a waste of time for the modern reader.

<comment> mark-r Even if your physical sensor is made of little squares, they cease to be squares once you've converted them to single readings - you've integrated the square into a single point. This is the basis of sampling theory. Continuing to think of them as little squares leads you to bad intuitions such as the resampling algorithm that we're responding to. Maybe there's a better way to make that point than the cited paper, but I haven't seen it yet.

Whether pixels are on the half-integer points is a completely arbitrary decision, unless you're trying to mix raster and vector graphics. Then the correct solution will become obvious.

<comment><USER2> From the point of view of sensors the square model seems correct. Sensor pixels are photon counters. If you want to turn a 2x2 pixel square into a single pixel summing the four pixels is the same as if you had a sensor with 1/4 of the pixels and each of them counts the photons over those 2x2 areas[1]. What we may be saying is that since you have the extra pixels you can actually do _better_ than if the sensor was already natively at your desired resolution by using a more complex filter over the extra data (e.g., by avoiding the Moiré artifacts that are common in lower resolution sensors).

[1] Most sensors are bayer patterns so some extra considerations apply to color resolution

</comment></comment></comment></comment></comment><comment><USER5> Let me insert my personal pet-peeve: have you thought of making it colour- space-aware? Most (all?) images you'll encounter are stored in sRGB colourspace, which isn't linear, so you can't do the convolution by just multiplying and adding (the result will be slightly off). The easiest way would be to convert it to 16-bit-per-channel linear colour space using a lookup table, do the convolution in linear 16-bit space, then convert back to 8-bit sRGB.

<comment><USER6> Color space conversion is a hard topic in terms of performance. First of all, not all images are stored in sRGB. Most of them have another color profiles (such as P3 or ProPhoto). So, sRGB conversion is not enough, you need the full color management.

Second, you'll see a real profit of color management only on a few images. Most time you'll see the difference only when you see both images at the same time on the same screen.

For now, I came up to the resizing in original non-linear color space and saving the original color profile with the resulting image.

<comment><USER3> By far most images in the wild are sRGB, and those that aren't should typically be tagged with their color space.

Resizing in gamma-adjusted space (sometimes) causes nasty artifacts when resizing. If you can afford the CPU use, always convert to an approximately linear space first, then downsize, then convert back. If you get the gamma curve slightly wrong (e.g. gamma = 2.0 vs. 2.2) it's not too big a deal, the resulting artifacts won't really be noticeable, so feel free to use a square root routine or something if it has better performance.

<comment><USER3> But note if you go to a linear space, you need to bump up the precision of your numbers. 8 bits per channel doesn't cut it anymore, you'll want 12 or 16 bits per channel (or even better, a floating point number). This might have a big effect on performance.

</comment></comment></comment></comment><comment><USER7> I'd be very interested in an optional Pillow-SIMD downsampling resize that produces 16 bit output internally and then uses a dither to convert from 16 bit to 8 bit. Photoshop does this by default and it produces superior downsampling. Without keeping the color resolution higher, you can end up with visible color banding in resized 8 bit images that wasn't visible in the source image.

I am curious if the reason that Pillow-SIMD is more than 4x faster than IPP is due to features IPP supports - like higher internal resolution - that Pillow- SIMD doesn't? The reported speeds here are amazing, and I'm definitely going to check this project out and probably use it, but I'd love a little clarity on what the tradeoffs are against IPP or others. I assume there are some.

<comment><USER6> Each resampling algorithm will internally produce some high-precision result before cutting it to 8 bits. For Pillow-SIMD it is 32-bit integers. Currently, I haven't considered dithering, but it is a very interesting idea. Do you have any links for further reading about downsampling banding and dithering?

About IPP's features: the comparison is pretty fair: the same input, the same algorithm and filters, pretty much the same output. If IPP uses more resources internally with the same output, so, maybe it shouldn't.

Shame on me, I still haven't added the link to IPP's test file I used. Here is it: [https://gist.github.com/homm/9b35398e7e105a3c886ab1d60bf598d...](https://gist.github.com/homm/9b35398e7e105a3c886ab1d60bf598dd) It is modified ipp_resize_mt program from IPP's examples. If you have installed IPP, you'll easily find and build it.

<comment><USER7> > Do you have any links for further reading about downsampling banding and > dithering?

Sadly, no, I wish I did. I just made some expensive mistakes printing giclee images from downsampled digital files, and whipped up my own dither for converting 16bit to 8bit. It wasn't until it bit me that I noticed Photoshop does it better than most apps because dithering is on by default. That's when I went looking and found an option for it in Photoshop's settings.

The main banding problem when downsampling is with slow changing gradients. Sky and interior walls, for example. I bump into it a lot with digital art too, since the source images don't have any noise. But even when there's noise in the source image, downsampling 2x or more with a good filter can eliminate the noise and cause gradients to stabilize and show their edges in 8bit color. In my experience, the problem is more common with print than on-screen resized images, but it's still pretty easy to spot on a screen, especially in the darks, and especially when jpeg compressing the results.

Implementation wise, the 16-to-8 bit dither is nowhere near as sensitive as the dithers we normally see converting 8bits to black & white or when posterizing. Almost anything you come up with will do. You don't need any fancy error diffusion or anything like that. Here's what I do: imagine the filtered 16 bit result as an 8.8 fixed point number in the [0-256) range, so the least significant bits are in the [0-1) range. I add a random number between -0.5 and +0.5 before rounding to the nearest integer. Viola, drop the low 8bits and the result is a dithered 8 bit value.

What I just described will be way slow in your world if you call a random number function every pixel, so don't do that. :P For Pillow-SIMD you'd want a random number lookup table or something slightly smarter than a random() function. And I dither on the color channels separately, but there might be some way to make it blaze by dithering the brightness and rounding all three channels up or down at the same time. I've just never tried to optimize it the way you're doing, but if you find a way and release anything that dithers, I would _LOVE_ to hear about it.

</comment></comment></comment><comment><USER8> Obligatory: [http://johncostella.webs.com/magic/](http://johncostella.webs.com/magic/)

</comment><comment><USER9> Unrelated: since when has this picture of Bologna become a new lenna.jpg?

I think I have already seen it in a couple of recent posts about image compression. (Fits perfectly the definition of Baader-Meinhof phenomenon [1].)

[1] [https://en.wikipedia.org/wiki/List_of_cognitive_biases#Frequ...](https://en.wikipedia.org/wiki/List_of_cognitive_biases#Frequency_illusion)

<comment><USER10> > Unrelated: since when has this picture of Bologna become a new lenna.jpg?

Lenna does IMO not contain enough sharp edges and contrasts to highlight the differences between the different resize techniques.

With Bologna, you can clearly see the problems with a nearest-neighbour approach. I'm not sure that would have been equally visible with lenna.

</comment></comment><comment><USER11> FWIW the Accelerate framework[1] gives roughly comparable performance[2] for Lanczos resizing. Apple platforms only, but all Apple platforms, not limited to x86.

[1] vImageScale_ARGB8888( ).

[2] I don't have identical hardware available to time on, and it's doing an alpha channel as well, so this is slightly hand-wavy.

<comment><USER12> Accelerate is a really amazing and highly underrated framework. Sure the function names are, uh, sub optimal (I'm looking at you, vDSP). That said, having a framework guaranteed across all devices to implement algorithms and primitives in the fastest way for each new device as they come out is amazingly valuable.

I've built production systems over the last few years with it that really wouldnt have been possible without it.

<comment><USER13> What kind of (server-side) production system can afford to only run on Apple consumer hardware? Or was it a mobile app?

<comment><USER14> IMGIX (a image scaling service) used to use Mac Pros [1]. Dunno if they still do though.

[1] [http://photos.imgix.com/racking-mac- pros](http://photos.imgix.com/racking-mac-pros)

</comment></comment></comment></comment><comment><USER15> Curious how this would compare vs. running it on the GPU? This is literally what GPUs are made for, and they often have levels of parallelism 500+ times greater than SIMD.

<comment><USER16> I tried to do this once with Theano, and found that the latency of the roundtrip to GPU and back made it not worthwhile for a single image. Maybe a batch of images at once would make it worthwhile. And this isn't what theano is intended for, admittedly - custom CUDA might do a better job.

<comment><USER17> I got curious about the numbers so I did a napkin calculation:

In a 2012 vintage Nvidia article[1] they get 5-6 GB/s in both directions (array size 4MB) which would be around 1500 Mpix/s with 8bit RGBA pixels.

15 Mpix image: Transfers both ways would take 20 ms, and given GPU kernel going at ~5x the CPU speed (CPU 30, GPU 150 Mpix/s), you would spend 100 ms doing the computation. So 120 ms on GPU vs 500 ms on the CPU.

[1] [https://devblogs.nvidia.com/parallelforall/how-optimize- data...](https://devblogs.nvidia.com/parallelforall/how-optimize-data- transfers-cuda-cc/)

edit: so I have no idea about the real GPU spedup, but this shows that the transfers shouldn't hurt too much unless the speedup vs CPU is very small.

<comment><USER15> Interesting, thanks. So it seems like it'd still be a pretty heavy win for the GPU.

Also, a common use-case on the web today is to have one input image and then a large number of output images (usually smaller) for different screen resolutions & thumbnails. Seems like you could save a lot of time by uploading the input image once and then running a bunch of resize convolutions for different output sizes while it's still in the GPU memory, then download the output files as a batch.

</comment></comment></comment></comment><comment> mark-r I'm really happy to see this. The one time I tried looking at the PIL sources for resizing, I was appalled at what I saw. Simply seeing that you're expanding the filter size as the input to output ratio shrinks is a huge deal.

When I wrote my own resizing code, I found it helpful to debug using a nearest-neighbor kernel: 1 from -0.5 to 0.5 and 0 everywhere else. It shook out some off-by-one errors.

</comment><comment><USER18> > No tricks like decoding a smaller image from a JPEG

Given that most cameras are producing JPEG now, I'm curious why you don't make use of the compressed / frequency-domain representation. To a novice in this area (read: me), It seems like a quick shortcut to an 8x or 4x or 2x downsample.

Or is the required iDCT operation just that much more expensive than the convolution approach?

<comment><USER3> That's a shortcut if you only ever have to downsample by powers of two and you don't mind worse image quality, since your down-sampled picture won't use any data from across block boundaries.

<comment> mark-r You can use it in a multi-step process. Use JPEG blocks to get slightly above the target size, then Lanczos to finish it off.

</comment></comment></comment><comment><USER19> Looks really nice!

I'd love to see vips in the benchmark comparison, perhaps a Halide-based resizer too as those are the fastest I've found so far. Perhaps GraphicsMagick too, as I believe it's meant to be faster than ImageMagick in many cases.

<comment><USER7> GraphicsMagick (GM) is definitely loads faster than ImageMagick (IM) for some resize operations, but I doubt it's in the same league as Pillow-SIMD, just guessing though. I've had to do some large image (gigapixel) resizing, and IM keeps the entire image in memory, which causes it to hit swap. GM streams the image resize instead, so it doesn't have to swap, and it can finish in a few minutes instead of many hours.

</comment></comment><comment><USER20> Another data point: MATLAB, glnxa64 AVX2, 12 core

>> maxNumCompThreads(1);

>> im = randi(255, [2560, 1600, 3],'uint8');

>> timeit(@()imresize(im,[320,200],'bilinear','Antialiasing',false))

ans =

        0.0083

>> timeit(@()imresize(im,[320,200],'bilinear'))

ans =

        0.0301

>> maxNumCompThreads(6);

>> timeit(@()imresize(im,[320,200],'bilinear','Antialiasing',false))

ans =

        0.0062

>> timeit(@()imresize(im,[320,200],'bilinear'))

ans =

        0.0113

Oh, missed that lanczos2 part:

>> maxNumCompThreads(1);

>> timeit(@()imresize(im,[320,200],'lanczos2','Antialiasing',false))

ans =

        0.0146

>> maxNumCompThreads(6);

>> timeit(@()imresize(im,[320,200],'lanczos2','Antialiasing',false))

ans =

        0.0049

Since MATLAB tries to do most of the computation in double precision, its harder to extract much from SIMD.

</comment><comment><USER21> Have you tried to use a fast blur (like StackBlur for example : [http://www.quasimondo.com/BoxBlurForCanvas/FastBlur2Demo.htm...](http://www.quasimondo.com/BoxBlurForCanvas/FastBlur2Demo.html) , the radius should be computed according to the ratio between original size and target size) as a first step before taking the classic nearest neighbor ? And also try to make an algorithm that resize to multiple resolution at the same time could improve speed

        I take an image of 2560x1600 pixels in size and resize it to the following resolutions: 320x200, 2048x1280, and 5478x3424

So you are also upscaling ?

</comment><comment><USER22> Great work and great article. One question though: Did you consider to replace convolution based filters by FFT based ones ?

<comment><USER23> For small filter sizes, convolution is going to be faster than an FFT approach. Plus, correct me if I'm wrong, but you need to perform a convolution for every output pixel where the filter kernel is different for each convolution (Sampling the lanczos filter at different points depending on the resample ratio), which would really slow down an FFT approach.

<comment><USER24> Beyond the mismatched signal size, the FFT approach creates circular convolutions, which is not what you want in images. You'd need windowing or a larger effective signal size, and pay the cost of conversions back and forth.

</comment></comment></comment><comment><USER25> > I wasn't building it for fun: I work for Uploadcare and resizing images has > always been a practical issue with on-the-fly image processing.

you ever consider pushing the work entirely to the client with a resize implemented in javascript? that would cut down on bandwidth as well.

<comment><USER6> It's exactly what my previous article "Image resize in browsers is broken" is about )

[https://blog.uploadcare.com/image-resize-in-browsers-is- brok...](https://blog.uploadcare.com/image-resize-in-browsers-is- broken-e38eed08df01)

It originally was written two years ago, so some things have changed. But in general, it is still correct: for most browsers, you need to combine several ugly technics to get suitable results. Though, the quality will have nothing common with quality when you have direct access to hardware.

<comment><USER26> Why not use asm.js instead of relying on canvas and hacking around browser problems?

<comment><USER6> 1\. asm.js is dead in favor of WebAssembly 2\. I need a solution for most browsers on most platforms, not for some very recent and most popular

</comment></comment></comment></comment><comment><USER27> Any reason this had to be a fork?

I would much rather this feature be in Pillow so ALL of the python ecosystem could get 6 times faster image resizing.

<comment><USER28> He addressed that in the article: Pillow is cross-platform and cross- architecture, so these sorts of specific optimisations (x86-64 only, with some pretty specific instruction requirements) meant that the author felt it wouldn't be a good fit in the original library

</comment></comment><comment><USER29> Looks fantastic! Are there other bottlenecks, such as JPEG encoding and decoding that can be ported to SIMD code in Pillow?

<comment><USER30> No, that's handled by libjpeg which can be replaced by libjpeg-turbo but nothing else at the moment.

</comment></comment><comment><USER31> Can the speed increased even further using GPGPU?

</comment><comment><USER32> > With optimizations, Uploadcare now needs six times fewer servers to handle > its load than before.

This is devil's advocate, but did you guys have concrete need for this optimization? You now need six times fewer servers, but was that a crippling problem, or is it a cool statistic for the future when you get more users?

<comment><USER28> One can make an argument that the CO2 and energy cost for wasted server usage is a decent reason for it! 6x fewer is not a small amount, that's a great result.

<comment><USER33> I thought this was in article already :)</comment></comment></comment>


Asus launches touchscreen desktop that turns into an 18 inch tablet - <AUTHOR> http://liliputing.com/2013/03/asus-launches-transformer-aio-touchscreen-desktop-that-turns-into-an-18-inch-tablet.html

<comment><USER2> And after a year, no more updates. I'm really frustrated that my TF201 isn't going to be updated to 4.2, the multiple users feature is a Godsend.

I don't understand why more manufacturers don't run stock Android, does it not help them upgrade more easily?

<comment><USER3> The manufacturers are all fighting to differentiate themselves from other manufacturers, to get sales, and justify more than razor thin margins. Often retail stores and their staff want the same - something exclusive. If you don't get into stores, you don't sell large quantities anyway, so the stores' wants are as important as the end users'.

<comment><USER2> Sure, but a tablet that gets updates more than a year later is a damn sight more exclusive than anything else out there, save the Nexus line :/

</comment></comment></comment><comment><USER4> Hmmm ... the idea of using it strictly as a remote desktop sounds intriguing, but do I really need the PC base-station then?

I use my iPad with a blue-tooth keyboard to work on remote computers quite a bit, so this basically gives me the equivalent with more pixels. The down-side is that it won't fit into a laptop bag.

Edit: I work in a similar way to what's described in this article - [http://www.linuxjournal.com/content/swap-your-laptop-ipad- li...](http://www.linuxjournal.com/content/swap-your-laptop-ipad-linode)

</comment><comment><USER5> That's an interesting form factor for a docking station.

It's also the first monitor to run Android...or the first tablet to allow an external device to display on its screen.

<comment><USER6> It's interesting that they felt the need to use Android when in tablet form, even though that's what Windows 8 was built for.

<comment><USER5> Maybe it's for hardware reasons -- can Win8 run on a Tegra? Would Asus have wanted to put an i7 in this tablet? (that might have actually worked pretty well, as it has the back surface area for a big battery and lots of heat dissipation...)

In a way, it's also like dual booting Android and Win8...

</comment></comment></comment><comment><USER7> Wow, that is a creative use of computing power. I am surprised it doesn't have a TV tuner so you can also use it as a TV.

Reading the Penny Arcade discussion about the Surface Pro made me wonder whether there is a niche market for a designer PC/tablet with something like Wacom pen support. Sit in front of is with CS6 and lay out something, pick up the display and lay it on the table like it would look like as a magazine cover, take a picture of a magazine cover with a rear facing camera and touch it up and back on the stand, moving back and forth. Probably wouldn't work for me but perhaps.

I was thinking about my notebooks and how a tablet could replace those. Something like the Galaxy note with a really killer implementation of something like Trello might do it. My note taking has never completely switched to a laptop because of the drawing requirement. Even with OmniGraffle which is pretty epically cool I can draw faster and more creatively it seems with a pen and graph paper.</comment>


Heathrow fined for USB stick data breach - <AUTHOR> https://www.bbc.co.uk/news/business-45785227 <comment><USER2> security through obscurity is weak security anyway</comment>


Ask HN: What to do with a contract restriction to not work with a competitor? - <AUTHOR> Being a citizen of Russia I am currently working for a company on Cyprus as a developer. I never wanted to stay and work here for a long period of time, the plan was to work a year or year and a half then take a pause and plan my further activity as I am more into creating my own consulting business or running one of my ideas as a startup. To add to the unwilling to stay long here, now I find working for this company quite demotivating, depleting my vision and objectives.
Now, as about 8 months of my staying here have passed, I am thinking of changing a company and stay here until autumn of 2017 or, who knows, a little longer. What can make this change complicated is the last contract clause, cited:
22. Upon termination of the Contract, the Employee shall not enter into any activity in any business, Company and/or partnership which competes, directly or indirectly, with the business of the Company or is/was a client of the Company. Such obligation shall last 2 years from termination of the Contract. It is contracted without any compensation from the Company whatsoever. It is not restricted to the territory of Cyprus.
As far as I understand, they don't want me to work for any company that can compete with them after I stop working with the company I work for now. Otherwise, how will it turn? I don't think (though just my personal assumption) they won't bother dragging me through courts to get any compensation.
Is this clause legit at all and common? Can I avoid problems with it if I want to work for a company that can be a potential competitor to them (who really can tell who is a competitor to whom clearly)?
What should I do if I get an offer from another company and decide to move on?
Please share your experience dealing with such things! <comment><USER2> Let me answer with a question: why are you asking HN instead of a lawyer?</comment>


Birchbox reached a deal, but it will leave some investors with nothing - <AUTHOR> https://www.fastcompany.com/40567670/heres-why-nobody-wants-to-buy-birchbox-even-after-vcs-spent-90m <comment><USER2> I recently sold a company that was in an ostensibly similar position. The information on this deal is incomplete, but here are my thoughts.

Given how lean they were running, they probably broke the covenants on their loan(s). This would make them "technically insolvent" \-- a very uncomfortable position for their (VC) Board members. Further, it's quite possible that the lender required a substantial number of Preferred shares as collateral.

So the company was probably in a bind, even if cash-flow positive.

Bankruptcy was probably not an option either. It kills any residual value in the company, as modest as that may be. And it requires Board and/or lender approval. A takeover by the lender would be more likely.

Another important dynamic to consider is that debt stands first-in-line for any proceeds. If necessary, all equity would become zero-valued if that's what's required to pay off the debt.

These are the reasons that debt is shunned in startups: if things go south, debt will make it 10X as bad. IMO, debt should only be used in healthy startups with predictable cash flows. The ability to make the payments isn't enough. The covenants are the first thing that bites.

With this as background, I would guess that management, debt, and the new equity got together and reached an accord that allows the company to try to get to a better place. Hopefully much better. The deal probably contemplates a strategic buyout within the next few years.

Disclaimers: I am a CEO -- not a lawyer, banker, or accountant. These are my opinions and analysis and I apologize to the parties involved if I got something wrong.

<comment><USER3> Thank you for the explanation. I came to the comments to ask how the company may be sold while the existing investors get nothing. It makes more sense to me now, but it still seems like the previous investors must have agreed to the deal. Perhaps it was easier this way than actually having to deal with bankruptcy?

On a different note, this quote bothered me: "We are prioritizing product innovation, the evolution of our digital experience, and scaled partnership opportunities," she says. This doesn't actually mean anything tangible. It may be CEO-speak for something meaningful or not.

<comment><USER4> Investors will sometimes agree to write down their equity to ~zero, if it's obvious that bankruptcy would yield the same result with more legal fees.

In this case, the previous investor was also the lender. So nothing above explains how they could end up with "nothing", unless that's counting only the equity and ignoring the debt.

</comment></comment></comment><comment><USER4> They're not too clear on the mechanics of this deal. Previous investors get diluted in a down round, but not usually to zero (especially given liquidation preferences, etc.). But:

> If Birchbox's venture investors had fought the deal — which they could have > done as debt holders who gave the company a lifeline in 2016 — the company > and its employees could have been staring down bankruptcy.

[https://www.recode.net/2018/5/1/17305940/birchbox-recap- viki...](https://www.recode.net/2018/5/1/17305940/birchbox-recap-viking- global-qvc-merger-sale)

So maybe they're saying that Birchbox's earlier investors accepted a deal where their equity became worthless, to preserve the value of their debt? Or maybe the "nothing" isn't strictly correct, and they just mean it's highly dilutive?

<comment><USER5> To me, "nothing" implies no equity and no debt owed.

So maybe they could have forced Birchbox into bankruptcy, but would have gained nothing except bad will. Or could there be tax implications?

<comment><USER4> From the facts reported, I don't see how they could come away with worthless equity and worthless debt. Whatever the tax implications, their liability should be limited--they could win the thing at the bankruptcy auction for $1, and then turn off all the lights and go home, only $1 poorer. So if someone wants to inject new money and keep running the business, then they should at least get some hostage value.

Maybe Birchbox has enough trade creditors with claims senior to the investors' debt to somehow wipe them out? That sounds pretty weird, though. If only all financial journalists were trained as securities lawyers...

<comment><USER5> I'm glad that I'm not the only one puzzled by this.

But as I said, I'm naive.

</comment></comment></comment></comment><comment><USER5> I'm just a naive guy, I guess. And I'm puzzled how new money plus hand waving can "leave some investors with nothing". Is it just that their investments had escape clauses? Or is this something like bankruptcy?

<comment><USER6> It's a matter of who gets paid first. To oversimplify...

Let's say I have a company with 100M in debt. If the company is sold for 150M. The first 100M goes to pay debt. The other 50M goes to the owners. If it's sold for 300M, then 200M goes to equity. They get all the upside. On the flip side if the company sells for less than 100M, the all the money goes to the debt holder.

What's going on is debt holders trade upside for downside protection. Equity holders give up downside protection to get equity.

Life is a little more complicated (some equity holders have more protection than others, and some equity holders may be debt holders) but usually it's just trading off upside for downside or vice versa.

<comment><USER5> OK, thanks.

So in this case, are you saying that the initial investors had equity, but held little or no debt? So they retain equity, but the company has no equity, so they have nothing? And the new investors are paying off debt to service providers etc? And also getting some equity?

<comment><USER6> When companies are worth less than their debt obligations, the debt holders get all the claims. This means all the revenue in a sale, or they can wind up owning the company. (This is oversimplified but directionally correct)

With Birchbox, one equity investor later provided debt. Others didn't. When the company dropped in value, the debt holder wound up owning the whole thing.

Sears seems to going through something similar at a larger scale.

</comment></comment></comment></comment><comment><USER7> Always a puzzle - if they were profitable (as they say), why did they need capital on these terms?

<comment><USER8> Two reasons:

\- profit != cash flow

\- 2016 profitable != 2018 profitable

<comment><USER9> I think the key question in parent comment was "on these terms". Getting financing for a profitable, growing business should not be this painful.

<comment><USER8> Yes, but just because they were profitable at some moment back in 2016, that doesn't mean that they're profitable today.

<comment><USER7> That's probably right.

</comment></comment></comment></comment></comment><comment><USER10> When a company refuses to release revenue figures -- which I assume is the case since neither this article nor the Recode article includes any -- its situation can't be very good, much more likely, it's very bad.</comment>


Show HN: Soft-launch, first page on HN – here are the numbers - <AUTHOR> [1/2]
Thursday evening (Mar 26) we made a soft launch for https://uidesigndaily.com (a UI website that I built for my wife)
The goal was to get some feedback, fix bugs and get about 30-40 subscribers in the mailing list, to see how the newsletter performs.
The launch went better than expected, and the feedback was generally positive.
Below are some numbers for those interested.
I posted it to 4 channels, IH, HN, Reddit and Twitter.
It was best received on HN with 203 points, it made it in the top 10, and it stayed on the front page for a good while. Reddit also surprised me, I posted in r/SideProject and got 26 upvotes and only positive comments.. ? That is so not what I expected from reddit... Was very pleasantly surprised to say the least.
Analytics: - 6.659 Users - 6,757 New Users - 7,906 Sessions - 19,125 Page views - 61.81% Bounce Rate - 10.1% Returning Visitors
Users timeline: - Mar 24 - 0 Users - Mar 25 - 4 Users [Soft Launch] - Mar 26 - 2458 Users - Mar 27 - 3693 Users - Mar 28 - 706 Users - Mar 29 - 186 Users - Mar 30 - 190 Users
As you can see, there's been a spike and seems like it'll stagnate around ~150, but it remains to be seen. It might dip even further.
Newsletter: - 546 Subscriptions - 52.1% Open Rate - 6.7% Clicks - 7 Unsubscribes
Slack Community:
40 Members. Interestingly enough, the Slack ad only received 30 clicks total. This means most users came through the welcome email, which has a slack community ad included.
Ad Performance: - 35744 Impressions - 836 Clicks on Website - 8 Clicks in Newsletter <comment><AUTHOR> [2/2]

Feedback/Critiques: \- Make the ads more distinguishable from the designs in the gallery. \- Subscribe popup on the post page comes in with delay and is annoying. \- Developers do not understand the software icons listed, they need labels. \- There was some confusion about the "open-source design" term, somebody thought it is created with open source software, instead of the design source file being available. \- Some developers don't know how to open the source files. A tip should be included that Figma is free and it opens up most file formats. \- Find a license that is more in line with our permissive approach. Maybe public domain?

Bugs: \- 13 different bugs found in production \- 79 total errors thrown in production \- 27 users experienced issues in production

Operational Cost: \- $8 - $13 per day, most of which is egress traffic and server log storage.

Conclusion: The soft went much better than expected, and it revealed some interesting insights about this project. We are going to make all the requested adjustments, fix the bugs, and prepare for the official launch.

<comment><USER2> $8 - $13 per day in operational cost seems crazy high for that many users where are you hosting?

Anyhow, congratulations on the website, I love it!

<comment><AUTHOR> Hey thanks a lot! Yep crazy high to the point of scary high lol. It's Kubernetes on Google Cloud. It is awesome no doubt, but man ... this could be ran on a $5/mo DO droplet. Was thinking of migrating tbh.

<comment><USER2> You should definitely before your proper launch, I don't think that amount of money is sustainable. You'd definitely be cutting in your margins for no good reason.

<comment><AUTHOR> I agree. I'll look into the DO Kubernetes offering, maybe that's more sustainable. I'd really like to keep running on k8s, but if it doesn't work out... I guess I'll just have to bite the bullet and do my walk of shame back to droplets.

</comment></comment></comment></comment></comment><comment><USER3> Cool product and thanks for sharing those numbers! Where did you post ads?

<comment><AUTHOR> Thanks! The ads are on the website itself. I wrote a custom ad service for it. Currently it supports 3 types of ads. 2 native ones in the gallery, and one on the post page.</comment></comment>


Unnecessarily Complicating Front-End Development To Feel Like A Smarter Person - <AUTHOR> https://medium.com/@julienetienne_/unnecessarily-complicating-front-end-development-to-feel-like-a-smarter-person-5e555fe650ed <comment><USER2> Sorry but the tone of this article rubs me a bit wrong.

Clearly the author didn't spend enough time in the bad old days maintaining massive piles of CSS and JQuery vomit to appreciate why modern approaches are the way they are. If an app approaches any degree of non trivial complexity on the front end, a framework like react or angular can really pay off. On the other hand, if we are just talking about a little vanity site or something that isn't going to need to be maintianed long term, by all means go old school. Just don't tell me that it's better in all cases because I've got the scars.

<comment><USER3> My experience and my scars are very similar. I remember the old days of maintaining piles of random JS and CSS -- it is not fun and it doesn't scale beyond blog-size without very good planning. I work for a huge national bank and I despise having to work on our older code. Sure, React/Angular/Redux have a learning curve -- but my company is able to deliver features at large scale _significantly_ faster (and with full test coverage!). I cannot overstate how much better developer quality of life has gotten.

I'd challenge people opposed to more complex frameworks to consider the challenge of delivering code at scale in the old-school style (say, Java EE with JSPs with shared components across multiple million-line applications, with 50% legacy code > 20 years old).

These newer frameworks were created for a reason. I had some doubts at first, but I've seen huge productivity gains.

I also don't care to hear complaints about "HTML in my JS". You only need to code a large application one time with a nest of document.createElement calls to see the rationale.

<comment><USER2> > I also don't care to hear complaints about "HTML in my JS".

Yeah that critique never held much water with me either. When JQuery and other "unobtrusive JavaScript" frameworks came out, it seemed really logical to separate the markup from the logic but, as applications aged and changed things started getting really hairy. I worked for one company that literally could not change any of their front end markup because they had tens of thousands of LOC that interacted directly with the DOM via class and ID selectors. Everything had to be done with CSS which of course led to massive CSS files with 30k lines. Working with something like that made me appreciate a more modular approach that React or Angular bring. Being able to compartmentalize your code into these logical blocks is MUCH easier to manage in the long term. One of the golden rules of programming is "write code thats easy to delete".

</comment></comment></comment><comment><USER4> I agree. With a little discipline, namespacing and a good project organization you can be very productive using only jQuery. No framework to learn, no need to update your app to the latest incompatible version (angular), you do not need to wait 6 months until you can hire a new developer.

The only thing that I would use is a CSS framework.

<comment><USER5> I am sorry, but modern frameworks such as Vue or React make you an order of magnitude more productive. And instead of waiting 6 months for a dev, I would consider training new ones.

<comment><USER4> Yes, you are more productive writing the easy stuff and then you loose time with esoteric bugs, configuration, training. Overall I would say less productive, but maybe this is only my experience.

<comment><USER5> Frameworks have improved immensely in the last few years. With Vue, I use the cli to generate the webpack project and then it works out of the box, bugfree (so far).

And then you can work with truly reusable single file components, and you don't have to manage the dom manually, ever (unless you want to). This alone is a game changer. It's like going from C/OpenGL to Unity3D.

</comment></comment></comment></comment><comment><USER6> Hype driven development appears in many disciplines. Javascript is exacerbated due to its lower barrier to entry (htmls/css hardly require cs degrees) but also how young everyone is, due to being mostly new developers.

There is some truth in this article. Younger people are more concerned with looking cool or smart. Due to the tone though, I suspect the author conpletely misses the point of many js frameworks.

An analogy i've been thinking about is tools to cross distance. From walking to cycling to driving to flying. No one will argue that a plane is just a fancy form of flying, with years of schooling and experience being unnecessary. However hardcore runners may look down on cyclists as they can have similar speeds yet maintain the flexibility of 2 feet for climbing, jumping, etc...

In this analogy, rather than distance as attrition(you can technically walk from sf to la for example), it's state complexity. I don't think complexity has grown to plane vs walking levels yet, and it's possible to consume your tools benefit by taking the long way b/c you can move faster (adding unnecesary complexity to use the complexity management tools). I think it's still important to understand and separate the original purpose of tools and their potential, and separate it from how it's actually used (often naively).

The article in the end is trying to create a schism and stratify developers rather than create understanding. That's something I highly disagree eith.

</comment><comment><USER7> Yup. Whole industry is wrong. No need for better tooling. Web development is easy /s

Making things more complicated by cargo cutting patterns isn't unique to the front end (looking at you, AbstractFactoryBuilderInjector dot Java). It is however different from using those patterns to reduce complexity or otherwise aide in the development of big systems.

<comment><USER7> s/cargo cutting/cargo culting

</comment></comment><comment><USER8> Regarding CSS:

\- I still need prefixes for old funky phones

\- I like or actually need SCSS (try changing the action color across a huge project without it or try overriding some CSS framework defaults).

</comment><comment><USER9> RIP mobile data wasted on meme-GIFs

<comment><USER10> None of the gifs hit 1kb. This is actually a pretty lightweight page. < 1mb loaded.</comment></comment>


Battle planning for supercomputer warfare - <AUTHOR> http://www2.warwick.ac.uk/newsandevents/pressreleases/new_research_provides/ <comment><USER2> As a simple benchmark for the capabilites of GPGPU software, I've been testing a hotplate simulation. In a 6400x6400 grid, the future temperature of each cell is an average of the cells around it. I've written it in C (single threaded) and it takes 40 minutes to run on an Intel nehelem. I've written it in Matlab and it takes 7 hours. Finally I wrote it in Matlab using the GPGPU plugin Jacket. It took 20 minutes. That's a 2x speed up over the serial code, with all the abstraction and overhead of Matlab. Next is a test in C with CUDA, but I was still very impressed with the performance of GPGPU in Matlab.

In our HPC lab, we see plugins like Jacket to be a valid substitute for translation of calculations from Matlab to C/fortran. While not the most efficient use of hardware, it is very simple to do and can drastically speed up many applications.</comment>


Examples of Automatic 3D reconstructions from photographs - <AUTHOR> http://paulbourke.net/miscellaneous/areconstruction/

<comment><USER2> Tangental random thought: I wonder if you could reconstruct a high-quality 3D concert from combining multiple pieces of low quality cell phone video taken by fans...

<comment><USER3> I looked at this briefly, and it would be extremely tough. Very few events have the kind of coverage (i.e., number of input videos) you would need to even get started on the problem. Plus, the conditions are just about the worst possible -- highly dynamic scene, low light, very unsteady cameras, almost all viewpoints in the same plane, low quality inputs, etc.

Note that the switchcam startup mentioned in the other comment is almost completely manual right now, and is more about assembling a "director's cut" version of a concert video, rather than creating 3d. This actually seems more useful to me (although of course more automation would be nice).

</comment></comment><comment><USER4> I've also gotten good results with ScannerKiller[1] from XYZRGB, for meshes where very high accuracy is needed/wanted.

[1] <http://www.scannerkiller.com/>

</comment><comment><USER3> This looks like an incomplete page, or perhaps a work in progress. Which method was used for generating each mesh? How many input images were there? What do they look like?

What's the takeaway message?

</comment><comment><USER5> I've used RunSFM (which uses bundler) to make 3D models from photos. It's cool, but you need to have lots of high quality photos for it to work.

I'd like to play with using a Kinect or simular 'depth camera', it might give better results.</comment>


Update on the New York Attorney General's Investigation - <AUTHOR> http://publicpolicy.airbnb.com/new-york-community-update/ <comment><USER2> I have taken a special interest in this story as I have been negatively impacted by having someone use AirBnB in my apartment building.

Every step of the way, from what I can tell, AirBnB has been at best deliberately obtuse and at worst actively lying. This post seems to be an example of the latter.

When AirBnB says things like:

> The vast majority of our hosts are simply renting out their own homes on an > occasional basis. The law was never meant to target them, and we now believe > the Attorney General did not mean to target regular New Yorkers either.

They are purposefully clouding the issue and making it seem like it is about things it's not. Renting out your home on any basis, no matter how occasional, is illegal if you are not present. It doesn't matter if you're a "regular New Yorker" instead of someone who operates a business renting out multiple AirBnB apartments.

The simple fact is that the vast majority of AirBnBs in NYC are illegal, and AirBnB has access to the data they need to fix the issue without significant cost to them, except for vastly shrinking their, illegal, market.

<comment><USER3> Can you elaborate on how you were negatively impacted? I haven't seen any first-hand accounts of actual negative impacts yet, just people speculating about things that might or could happen.

<comment><USER4> There is a discussion about this every month on HN. Here is the last one, many first hand accounts [https://news.ycombinator.com/item?id=7923849](https://news.ycombinator.com/item?id=7923849)

<comment><USER5> That top post was my first-hand account (and it's all true, so glad I left) but... let's not focus on the small picture of safety/quality of life.

The BIG picture is general cost of living in all major metropolitan areas where AirBnB has made in-roads. Fewer apartments/rooms available result in higher rents. This has been noticed all over the world (Amsterdam, Berlin, NYC, San Francisco). While I like the the basic concept of AirBnB (let no resource go to waste) the skirting existing rules/regulations which are in place for a good reason simply has to stop.

With regards to the AirBnB post in question, my best guess is that the DA has decided to require details on those properties which indicate actual illegal hotels. The most likely scenario for 'innocent' hosts is that they will need a permit, like Berlin, and in the process of applying for one, they will be vetted appropriately.

A recent CNet article outlines issues in cities other than NYC [1].

[1] [http://www.cnet.com/news/vexed-in-the-city-the-sharing- econo...](http://www.cnet.com/news/vexed-in-the-city-the-sharing-economys- hidden-toll-on-san-francisco/)

<comment><USER6> I understand that both NYC and San Francisco have rent control (either fixed rents or a maximum annual % increase), at least for some portion of the housing stock.

It seems like rent control creates consumer surplus for renters, at the expense of landlords. The use of AirBnB transfers some of this consumer surplus from the original renter to the temporary guest.

So, the combination of rent control and AirBnB-style short term rentals takes money from landlords (by restricting their return on capital to below the market level) and shares it between tenants (who become middlemen) and guests.

In cities without rent control, does AirBnB thrive to the same extent?

<comment><USER2> > It seems like rent control creates consumer surplus for renters, at the > expense of landlords. The use of AirBnB transfers some of this consumer > surplus from the original renter to the temporary guest.

We can obviously agree AirBnB is not the way to address this potential issue.

> In cities without rent control, does AirBnB thrive to the same extent?

I'd wager that less than 1% of AirBnBs are in rent controlled apartments in NYC. I'm sure rent control has a minor systemic effect, but rent control arbitrage is not the story here.

</comment></comment></comment></comment></comment></comment><comment><USER7> YouTube used illegal methods to succeed but there was no appreciable damage to anyone. The world was better for what YouTube did. Airbnb is causing actual pain in many people's lives and the problem is fundamental.

You simply can't invite dozens of strangers into apartment buildings without causing pain to the other inhabitants. Noise, damage, violence, and other issues are inevitable. Apartments are usually hellish enough with long-term tenants that are subject to real consequences.

No Airbnb employee or investor would put up with living in an apartment building full of Airbnb users. They'd go insane. But they do seem wiling to inflict this pain on others. That's evil.

<comment><USER2> Yep, that is what is making this issue distinct from, say, Uber and Lyft pushing the boundaries on regulation.

<comment><USER8> >> No Airbnb employee or investor would put up with living in an apartment building full of Airbnb users. They'd go insane.

Well there's your solution! That's some good out-of-the-box thinking right there.

</comment></comment></comment><comment><USER9> Their post talks about people "abusing" their platform. I'm taking that to imply that owning a property to list solely on AirBnB is "abuse".

Renting out an entire apartment can be selected to answer the second question on their signup process. [https://www.airbnb.ca/rooms/new](https://www.airbnb.ca/rooms/new)

Reading through the various hospitality pages, I don't see anything saying it's only to be used casually to rent out an apartment while you're away. The "Responsible Hosting" page ([https://www.airbnb.ca/help/responsible- hosting](https://www.airbnb.ca/help/responsible-hosting)) seems region specific, but still doesn't say anything along the lines of "renting on AirBnB full time is considered abuse".

For something they consider abusive, there doesn't seem to be any large warnings against doing it.

<comment><USER10> I believe they meant the term "abusive" in the relative sense of New York law, not in the relative sense of AirBnB or its terms of service. I interpret the statement as meaning, "abusing the AirBnB platform to circumvent or break New York law."

<comment><USER9> According to a different reply here, all postings of under 30 days are illegal.

I can't imagine only 140 of their New York postings are offering places for less than 30 days. There must be other selection criteria.

<comment><USER11> All "whole apartment" postings under 30 days are illegal. Sharing an apartment with a host is legal - though you may still be in violation of your lease.

I believe the term "abusive" here means "users whose behavior doesn't support our narrative of a populist/grassroots service". This would probably mean people who listed multiple properties, since that doesn't play into AirBnb's desired image as helping "regular people" make ends meet.

<comment><USER12> If you do a quick search of Manhattan, you'll see that a majority of their listings are of the illegal whole apartment variety.

</comment></comment></comment></comment></comment><comment><USER13> Warning, my post is loosely related to article. I want to share my experience using airbnb and the subsequent run-in with the law.

I recently used airbnb for the first time while visiting Washington DC. Unfortunately, my car was broken into while parked on the street overnight. The responding police officer inquired about where we were staying and I told him about airbnb. He has never heard of the service before. About an hour later the officer comes back and asks to speak with the landowner (who was out). The officer was about to give him a warning about operating an unlicensed bed and breakfast with the threat of a $1,000 per day fine.

</comment><comment><USER14> > First, this request represents an incredibly small fraction of our New York > hosting community – far less than 1 percent.

Good PR spin. Less than <1% of number of users "in our community"... providing 15% of the inventory. Whoops, leave that last part out.

<comment><USER15> Do you have a reference for that number? I wouldn't be surprised but would still want to see where you got that from.

</comment></comment><comment><USER16> A link for some background. I had no idea why this was an issue.

[http://skift.com/2013/05/21/airbnb-is-not-illegal-in-new- yor...](http://skift.com/2013/05/21/airbnb-is-not-illegal-in-new-york-city- but-many-of-its-hosts-break-the-law/)

</comment><comment><USER15> Interesting that they can just do that. It seems like twitter / google / facebook have taken a much stronger stance against this stuff, but I guess since AirBnB is still relatively "young" \- they're willing to jump through hoops a bit more.

Honestly - as an AirBnB host - this worries me.

<comment><USER17> Airbnb tried to fight it but they lost.

The fact of the matter is that most Airbnb listings in NYC are illegal, and pretty much everyone I know that lists their place on it is aware it's against the law. They do it anyways.

Airbnb is trying to cooperate as best they can without giving up too much of their users privacy as they need to get laws changed here in NYC (and other cities) if they want to keep operating in these markets.

<comment><USER18> > The fact of the matter is that most Airbnb listings in NYC are illegal

Full-apartment listings, yes. As I understand it, many listings renting out a shared part of the living space in which the leaseholder also lives (and is present) are legal, since that's considered taking in a short-term boarder, not subletting, which is allowed in NYC (and in fact protected as a tenant right, even if the landlord tries to ban it in the rental contract).

<comment><USER19> Last year, this fellow named Warren tried that logic in NYC. It didn't work too well. The Verge ran a piece about it back in May 2013.

> The law seems to include an exemption for hosts who rent out an extra room > or couch to a "lawful boarder" for less than 30 days, but remain in the > dwelling while the guest is there. Because Warren's roommate was home while > his Russian boarder was there, he argued that the exemption should apply. > However, the judge interpreted the terms "boarders and lodgers" in the law > to mean "occupants who share the life of the dwelling with its permanent > occupants" and not to "complete strangers who have no, and are not intended > to have any, relationship with the permanent occupant." Because the Russian > visitor did not interact with Warren or his roommate, the judge said, the > exemption should not apply.

That last sentence is an interesting interpretation of the judge's decision, but the rest of it is pretty spot on. The opinion in question is here: [http://s3.documentcloud.org/documents/702734/decision-and- or...](http://s3.documentcloud.org/documents/702734/decision-and-order-for- nov-35006622j.pdf) [PDF]

<comment><USER18> Ah, that's interesting. That seems like it would still allow a "classic" boarder, who interacts more with the household, including typically eating meals along with the household rather than only renting a room (as in "room and board"), not purely renting out a room. But probably safer if there is also some other connection (friend-of-a-friend, etc.), reading the other bits of the blurb.

<comment><USER19> Yeah, it seems like the judge is making an effort to let you have friends and friends-of-friends, just not customers. It's worth noting that this is an opinion from Administrative Law Judge, which is about a half-dozen appeals from the State's highest court, the Court of Appeals. So there are plenty of judges who could overrule this in the next few years.

</comment></comment></comment></comment></comment></comment><comment><USER20> a huge number of airbnb hosts in NYC are flagrantly breaking the law. this causes significant harm to the permanent residents of New York and the attorney general should do everything in his power to prevent these illegal rentals.

</comment><comment><USER21> It seems that airbnb will be forced to face the music and adhere to zoning laws and other regulations sooner or later, at least in dense, mostly- apartment cities like New York. I think airbnb is cool, so I hope they choose to comply and assist people in offering legal rentals before this blows up and they go the way of Napster et al. Sometimes, startups need to adapt, just like bigger companies.

</comment><comment><USER4> Maybe I am one of the people advesely impacted by the the 1% "bad actors" in Chicago. But its simply not fair for them to say because its just a small percentage of hosts we should just ignore it.

I just want airbnb to go away. For god's sake please go away. Please ban this website, put the owners in Jail.

</comment><comment><USER22> This made a lot more sense with the original title: "Airbnb to Out 124 Hosts to New York Attorney General". The new title gives no indication at all as to what this is about.

<comment><USER15> Agreed - sometimes sticking to the post's title is a detriment to the reader.

<comment><USER12> I've noticed a distinct pro-Airbnb slant to coverage on HN, so this is in keeping with that pattern.

<comment><USER15> Well YC has a big investment in them obviously.

That said - I'm very pro-airbnb, but I _still_ really need to know about this in case they decide they're going to operate like this in places outside NYC>

<comment><USER12> Considering that the majority of their business in NYC is illegal sublets and they're well aware of that fact but lie about it - and purposely mislead the public about it in their commercials and public statements - doesn't exactly paint them as a good player in locations outside NYC.</comment></comment></comment></comment></comment>


How we got gripped by the hand-held device - <AUTHOR> http://aeon.co/magazine/technology/how-we-got-gripped-by-the-hand-held-device/ <comment><USER2> Funny - the author divides hand-held images through history as work-related (the people) vs authority-related (the ruling class) e.g. swords, books. Then they go on to wonder why the iPhone is the great equalizer, since it is work- related and the rich and poor alike hold one.

I wonder why a phone is arbitrarily labeled work-related, and not ruling- related. It serves to free us from communication tethers, allow entertainment/socialization anywhere, give instructions and get advice. More like a ruling class tool than a shovel.

</comment><comment><USER3> "Chaplin's Law: every eventual hand-held device has shrunk from an earlier portable incarnation, one that had to be borne by two hands, if not an arm or two flung companionably round it."

The magnifying glass - icon of detective fiction, daily tool of jewelry appraisers, and source of the modern symbol for 'search' \- did not have that progression.

Nor did writing utensils. I have a pen in my pocket right now.

Overall though, an enjoyable read.</comment>


Print is dead. Long live print - <AUTHOR> http://www.cjr.org/special_report/print_analog_comeback.php <comment><USER2> I think this is why indie magazines are starting to thrive in their niche; even younger readers are appreciating the aesthetic and value of print as a resource AND art form.

<comment><USER3> At the end of the day attention is the only finite resource. Everything else is infinite. If you have something worthy of my attention, then I might just pay you for it. It has nothing to do with print or infinity. It has everything to do with the value proposition. Mass media has very little value proposition when put against its competitors. Other things might not. Things that you care about that are harder to find. That are easier. That are prettier. That appeal to identity politics like vinyls and other retro things. That make you a hipster or a snob. That differentiate you from the poseurs.</comment></comment>


Employee monitoring: When IT is asked to spy - <AUTHOR> http://www.computerworld.com/s/article/print/9177981/Employee_monitoring_When_IT_is_asked_to_spy?taxonomyName=Careers&taxonomyId=10

<comment><USER2> I've been on both sides as well. But here's the deal... as the spying IT guy, you have to be super careful. Do not be afraid to tell your employer that you do will not do something if you think it puts you personally in a bad legal position.

I had one of our legal guys at a job request that I manually review email logs to look for something for him. My response to that was simple, "fuck no." I'll grep for strings and patterns and pull you the emails that come up, but there is no way in hell I am reading someone else's email.

The reason is pretty simple too. I don't want to be a part of your lawsuit. I don't get paid to be subpoenaed and deposed. If I quit this job or am laid off I don't want to be getting called up a year, or three down the line just to show up in court and answer questions about why I was reviewing jane and john smith's emails to their kids.

Simple fact is, at some point you have to be willing to tell an employer that what they are asking you to do goes way beyond your pay grade. And protecting yourself legally comes before anything related to your career advancement.

</comment><comment><USER3> Just another instance of applying a wrench to a nail. Why is it that the receptionist/phone operator isn't asked to listen in on phone calls? Why isn't she responsible if someone says something stupid over the phone?

If someone is killing time on facebook to the point that it's affecting their work then the manager should notice the lack of productivity regardless of the cause. Otherwise if it's not affecting their work then why does it matter?

It's a means of abdicating managerial responsibility. The boss doesn't have to be the bad guy anymore now it's IT.

</comment><comment><USER4> I was once the IT administrator at a company for many years, and my policy regarding spying on internet/email communications was that unless something came to my attention which warranted surveillance of an individual all user communications would be treated as private and confidential (the same as regular snail mail). I'd previously attended a security seminar where they made clear that, at least as far as the laws in the UK were concerned, if you intercepted an employee's communications or read their emails the reason for doing that must be one which would stand up to scrutiny in a court case. Without any specific legally defensible justification, "trawling" style spying on communications lays the IT administrator exposed to possible criminal charges.

However, all that was more than five years ago, so things may have changed since.

</comment><comment><USER5> I've been on both sides of this. No one wins.</comment>


Why "Remember Me" Should be Above the Login Button - <AUTHOR> http://blog.jasonshah.org/post/17611119522/why-remember-me-should-be-above-the-login-button

<comment><USER2> I like your reasoning, but wouldn't that kill the UI of a login modal? Why not just automatically have 'Remember Me' boxes checked instead?

<comment><AUTHOR> Hey Case -

Fair point. By 'kill the UI login modal', do you mean that it would be inserting something between the text fields and the login button, therefore disrupting the flow in some way? If so, I can see that.

The only problem with having 'Remember Me' auto checked is that I feel like a lot of users get bothered by it. At least personally, even when I WANT to eventually check the box, I feel like having it done for me takes the agency away from me and comes off as slimy. So, if we ran with that view (which I understand may not be the case), then it would be the next best thing in my mind to place 'remember me' higher in the flow.

<comment><USER2> Hey Jason yeah that is what I was trying to say. Login screens are so second nature to people: username, password, login... that I wonder if that extra check in between would throw them off.

I agree that the auto check does come off slimy at times, but I think I get more annoyed when I have to login to a site again vs. seeing that they already checked a box for me. Either way you have a solid argument. I'd really like to see someone do some A/B testing on this. Oh, and thanks for the response.

<comment><AUTHOR> Yeah, in this case only data can suggest which would be the best UX route. Some A/B testing around percentage of visitors who come to the home page and login with either layout (some permutations of Remember Me checked/unchecked, Remember Me above/below login) would be interesting. Perhaps instead focusing on login pages and how they layouts perform there (vs. the home page) might be more precise because I wonder about all of the other noise that may come into play on a home page and if that noise could interfere with the precision of the testing.</comment></comment></comment></comment>


Why Google changes name to Alphabet – Larry Page gives full details - <AUTHOR> http://www.techlug.com/2015/08/why-google-changes-name-to-alphabet-larry-page-gives-full-details.html <comment><USER2> The business of starting businesses, interesting..</comment>


Show HN: Build Your Visual CV - <AUTHOR> https://www.somewhere.com/visualcv

<comment><AUTHOR> A better way to create a CV/resume - people don't know how to talk about work but if you ask the right questions, you get interesting answers.

There's a lot more on the site, but we're experimenting with an idea about dropping down the adoption curve and making stepping stones to provoke a kind of behavioural change.</comment>


A Scalability Roadmap - <AUTHOR> https://bitcoinfoundation.org/2014/10/a-scalability-roadmap/

<comment><USER2> To the people who said that Bitcoin is a failure because it can't scale, reading this must be beautiful. Bitcoin will scale to "Visa network" levels in no time.</comment>


Campaign urges BBC News to release full text RSS feeds - <AUTHOR> http://www.journalism.co.uk/2/articles/535000.php

<comment><USER2> The Guardian (disclaimer: my employer) are one of the only newspapers in the world to provide full content RSS feeds: [http://www.guardian.co.uk/help/insideguardian/2008/oct/22/fu...](http://www.guardian.co.uk/help/insideguardian/2008/oct/22/full- fat-rss-feed-upgrade)

<comment><AUTHOR> are you the simonw involved with the API project?

<comment><USER2> Yes, and the MP's expenses project.

<comment><AUTHOR> Awesome. We're based in Cambridge [UK] so if you ever want to chat news over a beer ...

<comment><USER2> I don't get up there often, but the Guardian is right next to Kings Cross - drop me a line at simon.willison@guardian dot couk if you're in the area.

</comment></comment></comment></comment></comment><comment><USER3> Given that the tax payers (and I'm one of them!) fund the BBC, we shouldn't be needing to demand this from them. They should've done it ages ago without prompting. It's our money that paid for it and we should have unfettered access.

Come on Beebs, release your feeds!

I'm seeing a parallel to government funded academic research that comes with stipulations that the resulting publications should be Open Access.

<comment><AUTHOR> that was kind of my point, but I didn't want to sound too aggressive by saying that

yet ;)

<comment><USER3> Well someone needs to hammer the point home.

Also, this may fall on very favourable ears: part of the most recent govrenment, ummm, cabinet improvement was a move to open up the UK government's data. RWW has a nice piece on it: [http://www.readwriteweb.com/archives/open_goverment_berners-...](http://www.readwriteweb.com/archives/open_goverment_berners- lee_and_the_uk_to_show_obam.php)

And who's in charge of this? None other than Tim Berners-Lee.

<comment><USER4> Hmmm.... I wonder if they'll let him do what he really wants to do with it? The UK govt has made a number of high-profile - dare I say, "celebrity" - appointments at the moment (see also Alan Sugar, Martha Lane Fox). So do they want the best person for the job, or is it just a matter of the publicity and the prestige? As a citizen, I think TBL is an excellent choice for the job. Will the govt be able to stomach his changes? I sincerely hope we don't see him resigning from his post in 6 months, citing "unassailable differences of viewpoint with his employer".

</comment></comment></comment></comment><comment><USER5> For UK readers, the majority of which are license fee payers, I agree.

But I'm not sure about international visitors as the BBC generates revenue from ads shown on their site, so I'm not sure if it would make sound financial sense and be good use of the taxpayers money if it would impact their revenue stream. The downside is that people using online readers would be hit in the cross-fire, but that's unavoidable.

<comment><AUTHOR> what ads?

<comment><USER5> The BBC shows ads on its website to non-UK visitors and have done since 2007. From [http://www.bbc.co.uk/pressoffice/bbcworldwide/worldwidestori...](http://www.bbc.co.uk/pressoffice/bbcworldwide/worldwidestories/pressreleases/2007/10_october/bbc.com.shtml):

"The BBC Trust has approved proposals for the BBC to establish bbc.com, a commercial venture to offer advertising on the BBC's international online service for users outside the UK. UK users' experience of bbc.co.uk will not be affected.

...

bbc.com will use robust geo-IP technology (see Editor's Notes) to separate out international visitors to the site."

From these ads, they made £1.5m ($3m) in the 5 months after launch (from the BBC Annnual Report at [http://www.bbcworldwide.com/annualreviews/review2008/Digital...](http://www.bbcworldwide.com/annualreviews/review2008/Digital_Media.aspx)).

<comment><AUTHOR> they should just put them in the full article feed, then

</comment></comment></comment></comment><comment><USER6> This would be pretty useful. The best use of the BBC's RSS feeds that I've seen was on a ferry and they had BBC screens showing the latest news.

</comment><comment><AUTHOR> here's the direct url: <http://bbcfree.net>

</comment><comment><USER7> Until they do implement this, there's always <http://fivefilters.org/content- only/></comment>


Ask HN: Briefly and succinctly – when is ML helpful for engineering? - <AUTHOR> Given how ML is now the cool thing, I realize this may make me look, um, not cool:
How would you describe what ML can offer me, a non-ML-saavy tech organization?
When does it work better than manually programming something?
Which kinds of data work best?
How extreme of data can the model be fed before giving non-sense results? And will it "know" how hard it is guessing?
What is the format of its results?
... etc ...
Tangentially, I may have many, many more follow-up questions.  Are there any freelance "AI Consultants"? And if so, where best to find them? <comment><USER3> I'm still learning too, so take the following hand wavey reply with a grain of salt..

What can ML offer?

ML allows you to more easily make predictions from data you already have. An example is taking search terms and grouping them into their subject matter, or taking images and identifying things inside them visually. If you deal in sales, you could predict future sales based on other factors that you believe are correlated (weather? clicks?). If you deal with customers, you could more quickly identify what type of issues people are having (hardware issues? card failures?), or proactively suggest solutions.

Better than programming:

It works better when, to code a new feature, you'd need an abundance IF statements whose logic you'd have to work out by hand. In a very broad way, the machine is figuring out how to approach your task just with lots of examples and scary math. You can get a lot of different "answers" without having to write that much more code, just by trying different data and structures.

Practically it's easier than programming to keep updated as well, because if you can find example inputs that it guessed wrong, you can get automatic improvements to results by retraining with correct predictions.

But of course, the ML system itself is very complex, and it involves a lot of resources to design it, curate input data, and train on costly GPUs. This combination of the system's design, and the learned state of the systems innards, is called "the model".

Input data:

There are many different ML systems designed to use different kinds of input. Some use pure text, image data, audio data, graphs of interconnected thingies. The easiest is when the data is very uniform in structure, grouped into labeled columns (called "features"), with each column having a meaningful value. To train the system, you must also supply a "target" feature for each record, which are examples of what you'd like the system to predict. Anything that fits naturally in an Excel sheet might be a starting point. Generally, you want quite a few examples, but the exact amount of data you'd need varies with how difficult your task is.

Bad input, bad results:

Varies. From the practical side - ML systems usually produce confidence scores which you can use to avoid embarrassment. You can then manually label those confusing examples and feed them back in for training. In terms of the model itself - there are many ways of interpreting and evaluating accuracy, and the system can give you examples that confuse it.

Results, two common examples:

Some systems produce a number as their output - called regression. (Picture a sales prediction.)

Others group things into a set of pre-defined categories - <USER2> classification. (Picture a system that can tell if there's a giraffe in an image.)

What those outputs mean, and how they are to be used, is part of the design of the model.

<comment><AUTHOR> This was extremely helpful, thank you!

Perhaps you can help me with some follow-up questions:

\- Let's imagine a standard excel sheet (a 2d array), with columns "A", "B", "C", "D" ... "Z".

1) Let's say I want to create a model, that takes this input: A single row where all columns have values, except for some (random) columns. I want it to autopopulate those columns with values that are most probable according to the data I trained it with. That is, _every_ column is both a "feature" and a "target". Is this possible?

2) Can I train the model by telling it this: "This input should DEFINITELY NOT confuse you" \-- that is, can I "weigh" the inputs (or do I just put in more of them?)

<comment><USER3> 1\. You can predict multiple values, but it still has to be trained on target values for those features. So, you could predict "D", "P", and "Z", but not any at random - you'd have to design it that way. Look into "multidimensional regression"

2\. That seems logical -- supplying a "confidence level" with the training data itself -- but I haven't heard of it, and can't seem to find anything on the search engines.</comment></comment></comment>


Ask HN: Will Apple release cheaper Macs? - <AUTHOR> I was wondering as Apple moves to use their own SoCs would it be possible for them to lower prices?<p>For reference: the current Intel-based Mac mini starts at $799 while the iPhone SE (A13) starts at $399. <comment><USER2> Apple's pricing of their hardware has almost always been a premium model. The component cost rarely correlates with the sticker price. Some of that is due to brand, but Apple also spends a lot of R&D working on manufacturing techniques.

I think the most standout price for Macs was the original Mac Mini, which was just $500. That was mostly an effort to get Windows users to switch platforms.

In short, I don't think Apple Silicon machines are going to result in a lower price. I think the higher price tags are part of Apple's culture at this point.

</comment><comment><USER3> The new Macs will be somewhat cheaper to make and Apple will want to build market share to support Mac SoC development costs but question I think is whether they can do so without damaging their ability to charge prices similar to current level for their premium products.

So they need something that distinguishes from current range as body style does for SE vs iPhone 11.

</comment><comment><USER4> Cheaper to build? Yes.

Lower prices, why? Apple wants their Mac line to have higher profit margins like their more successful products.

Apple may well have a wider lineup like a MacBook SE but then you're getting less.</comment>


Banks Bundled Bad Debt, Bet Against It and Won - <AUTHOR> http://www.nytimes.com/2009/12/24/business/24trading.html

<comment><USER2> When you consider the human consequences of this sort of unethical behavior, it's quite horrifying. It's like me selling you a car that I know is faulty, then betting that you'll have an accident.

</comment><comment><USER3> Investment banks seem to have two parts, one part is concerned with making trades to benefit the bank itself. The other part is a broker that helps clients with what they need.

I don't think the same bank should be allowed to do both. At the very least there should be a firewall between the departments.

<comment><USER4> No, in practice the same trader will make the trade and make another trade to hedge against losing money on the first. That's normal.

What's _wrong_ here is acting in bad faith by selling known-bad investments. At best it's insider trading, at worst outright fraud.

<comment><USER5> Any time you sell a security, you are selling a security which you believe to be a bad investment. If you buy at the bottom and sell at the top, the guy you sell to will lose money.

Take their deal with Hudson Mezzanine. Goldman offered Hudson a bet: if the housing market goes down, Goldman wins, if it goes up, Hudson wins. Hudson lost. What's the problem?

<comment><USER4> _Any time you sell a security, you are selling a security which you believe to be a bad investment._

Firstly, that's not true if you're a "market maker" as many large banks are. Secondly, it's not true if you are selling for a reason (e.g. you need the cash to do something else with) or for a technical reason (e.g. you are an index fund). Thirdly, so long as you are not actively misleading the buyer, if he thinks it's worth that much, that's his call.

<comment><USER6> >> Any time you sell a security, you are selling a security which you believe to be a bad investment.

> Firstly, that's not true if you're a "market maker" as many large banks are.

Actually, it's always true. You sell things because someone else is willing to pay you more for them than you think that they are worth to you. You buy things because they're worth more to you than the money it costs to get someone else to give them to you.

Yes, there are lots of reasons why your valuation is different than the other party's, but the difference is why both of you are willing to do the deal.

> Thirdly, so long as you are not actively misleading the buyer, if he thinks > it's worth that much, that's his call.

Absolutely. The buyer is willing to take the "profit", so he should be willing to take the loss. (The seller has similar issues - if they sell for "too little", that's their problem because they were willing to take "too much".)

<comment><USER7> > Actually, it's always true

There are such things as "gains from trade", you know. Not all assets are worth the same amount to all players! If you buy an asset that you think anticorrelates with your other assets to reduce variance, you don't need to think that asset is underpriced. And if you need to liquidate some of your assets to return to shareholders or, heck, buy a house, we call that "liquidity preference" and it means you don't necessarily think the asset is undervalued, just that cash in hand is worth more _to you_.

<comment><USER6> > Not all assets are worth the same amount to all players!

I wrote that trades happen because the parties value the relevant asset differently (the one that starts with the asset thinks that the cash is worth more than the asset to it, while the other thinks that the cash is worth less to it), so "correcting" me by telling me that is curious....

> to think that asset is underpriced

I didn't say anything about "underpriced". I said that the two parties had different opinions about the assets in question wrt themselves. They can both be correct. (They can also both be wrong.)

</comment></comment></comment></comment></comment></comment></comment><comment><USER4> It's a fine line. If you insure your car are you "betting" that you'll crash it? No of course not. But having insurance doesn't mean you can be reckless. Your insurer wouldn't pay out - and neither should the various governments that did.

</comment><comment><USER8> single page link: [http://www.nytimes.com/2009/12/24/business/24trading.html?_r...](http://www.nytimes.com/2009/12/24/business/24trading.html?_r=1&pagewanted=all)

</comment><comment><USER9> it's called moral hazard. it is well known in the insurance industry.

lately I've been struck by the obviously directly related tendencies to

A) ignore history

B) act like everything is new

</comment><comment><USER10> cunts

<comment><USER10> obvious things don't need to be expanded upon.</comment></comment>


Amazon Local to Stop Selling Daily Deals on December 18, 2015 - <AUTHOR> https://local.amazon.com/help <comment><USER2> Came here to post this. I'm glad the "deal site" craze is winding down.</comment>