derf_

17 ms·

151.
by derf_ 3y ago
It is possible to put filters on function arguments, e.g., the definition f[x_Integer] := ... will define a rule for f[] that only matches expressions where the argument to f[] has the head "Integer". It is even possible
152.
by derf_ 3y ago
A great way to visualize this is by looking at the "consumer surplus", the red region in this graph: https://en.wikipedia.org/wiki/Economic_surplus#/media/File:E... [1] The value created by a sale,
153.
by derf_ 3y ago
> (I don't think fractal compression can be fit into this framework, but I could be wrong. That's the only exception I can think of offhand.) See https://ieeexplore.ieee.org/abstract/document/660992
154.
by derf_ 3y ago
The author talks about JPEG, and says the principle is surprisingly similar, but the connection between the two is actually pretty direct. I will link a previous comment of mine from another discussion of SVD image compression to explain:
155.
by derf_ 3y ago
> So it's not like you can say 'all IEEE standards should be patent free'. What? Sure you can. See the W3C patent policy, as one example: https://www.w3.org/Consortium/Patent-Policy-20200915/ T
156.
by derf_ 3y ago
Back in the early 2010's I had a cheap Dell laptop with a 6-bit panel and an integrated Intel GPU. Video on that device had incredible banding, almost all the time, because as I understand it, the Linux drivers were relatively immatu
157.
by derf_ 3y ago
Memory pressure is even worse on GPUs. I did some work to generalize Blelloch to 2D parallel prefix sums for integral image computation back in 2008 [1], and the number of memory accesses really dominates. On a GPU, for sufficiently small p
158.
by derf_ 3y ago
It gets worse than that. On x86-32, you are only guaranteed 8-byte stack alignment, and if you try to use __attribute__((aligned(16)) on a stack variable, gcc just silently fails to enforce the alignment. Or it did 15 years ago when x86-32
159.
by derf_ 3y ago
You run into these problems on x86, also, with SIMD intrinsics like _mm_cvtepi8_epi32() (which converts four 8-bit integers to 32-bit integers with sign extension). The underlying instruction, PMOVSXBD, when used with a (4-byte) memory oper
160.
by derf_ 3y ago
If you will permit me to tout things I worked on while there, Opus seems to have been pretty successful? The final story has not yet been written on AV1, but it is still the best chance we have had for a royalty-free video format and thanks
161.
by derf_ 3y ago
I would not say "easily"... patent holders will absolutely try to avoid the effects of exhaustion by imposing post-sale or field-of-use restrictions, but lawsuits about it have gone to the Supreme Court, e.g., https://s
162.
by derf_ 3y ago
> There is no analog for the first sale doctrine... There is. It is called patent exhaustion. See https://en.wikipedia.org/wiki/Exhaustion_doctrine_under_U.S.... There was a fad of issuing a "covenant not to
163.
by derf_ 3y ago
My understanding (now several years out of date) is that Arm decided not to pursue licensing a design, because every customer they talked to had requirements that were so different that they would have essentially been one-offs that each re
164.
by derf_ 3y ago
No, because all real employment contracts (and most other contracts, besides) will have a Severability clause that says if anything in it is found to be unlawful or unenforceable, then the contract will be modified to the minimum extent req
165.
by derf_ 3y ago
Thanks for running these examples. If there were timings for the final algorithm in the article I missed them, so it was hard to tell how much A* was really speeding things up. You have convinced me that it is worth specializing for a parti
166.
by derf_ 3y ago
> 2^32 bytes is 4GiB so a bitmap would be 512MiB. Yes, sorry, 2**27 32-bit words, so 512 MB. >However a downside of A* is that I need to store the depth in the visited map as they may be found out of order. I also store the move th
167.
by derf_ 3y ago
I wrote one of these to solve the daily challenge at the now-defunct < https://www.robotreboot.com/challenge >. Four robots, no mirrors. I did not bother with an A* search or robot sorting, because each daily challenge
168.
by derf_ 3y ago
The best explanation I heard after the great financial crisis (i.e., not recently) was that during that crisis, the Japanese bubble economy of the 80's, and to a lesser extent the dot com crash, huge amounts of credit (marked to market
169.
by derf_ 3y ago
> In practice this clock is generated via the PC clock so it isn't the same clock at all... Yes, that is the point. WebRTC has to work with cheap / commodity hardware running a general purpose OS with clocks that are not sync
170.
by derf_ 3y ago
> I have had no problems with measuring NTP drift. Yeah, their claim is just weird. RTP does not impose an accuracy requirement on its timestamps (despite the name "NTP timestamp" in the Sender Reports, they are not actually
171.
by derf_ 3y ago
In the 1974 political thriller The Parallax View, one of the characters boards a plane at LAX, and then purchases a ticket from the stewardess. It is the most jarring scene in the entire film.
172.
by derf_ 3y ago
> I guess the circulatory system is like that too... I have some news for you: https://en.wikipedia.org/wiki/Circle_of_Willis
173.
by derf_ 4y ago
With one memo, Stephen Elop [1] drove Nokia's market cap from its peak of over $57b in March of 2010 to a trough of less than $7b in July of 2012 [2]. [1] https://communities-dominate.blogs.com/brands/2011/08&
174.
by derf_ 4y ago
https://hydrogenaud.io/index.php/topic,114566.msg1023511.htm...
175.
by derf_ 4y ago
They relaxed the need for a capital conservation buffer, too. These actions were part of the Fed's response to the market panic at the onset of the pandemic, and you can read a bit about their reasoning in their own press release: htt
176.
by derf_ 4y ago
I think you have misunderstood Buffett theory. Most (i.e., more than 50%) of actively managed funds underperform, but in aggregate the amount of underperformance across all funds is roughly equivalent to the management fees they charge. Ima
177.
by derf_ 4y ago
https://academic.oup.com/qje/article/135/4/1965/5858010
178.
by derf_ 4y ago
In 2010, I tried to use callgrind to profile a project on Arm, after having used it to great effect on x86, and discovered that because of the variety of ways to return (and call!) functions on Arm, callgrind was unable to reliably identify
179.
by derf_ 4y ago
> Is there a smart way to store the basis vectors? Consider, instead, compressing small blocks of the image instead of a whole image plane at once. Let's say 8x8. Over such a small region, pixels are usually very highly correlated
180.
by derf_ 4y ago
No, you still owe the stock, but if trading is halted or the stock's registration is revoked, you cannot close the position. That means that (a) you still owe (daily!) stock borrow fees, and (b) you are still required to keep collatera

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