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owlbite commented on Algorithms for Optimization [pdf]   algorithmsbook.com/optimi... · Posted by u/Anon84
sfpotter · 21 days ago
Can anyone provide a comparison of this book to Nocedal and Wright's book?
owlbite · 21 days ago
This book provides a high level overview of many methods without (on a quick skim) really hinting at the practical usage. Basically this reads as a encyclopedia to me, whereas Nocedal and Wright is more of an introductory graduate course going into significantly more detail on a smaller selection of algorithms (generally those that are more commonly used).

Picking on what I'd consider one of the major workhorse methods of continous constrained optimization, Interior Point Methods get a 2-3 page super high level summary in this book. Nocedal and Wright give an entire chapter on the topic (~25 pages) (which of course still is probably insufficient detail to implement anything like a competitive solver).

owlbite commented on I may have found a way to spot U.S. at-sea strikes before they're announced   old.reddit.com/r/OSINT/co... · Posted by u/hentrep
somenameforme · 2 months ago
100% agreed with this and this is one of the worst issues about the development of long range weapons. 'We droned this guy.' 'We bombed this area.' 'We destroyed this boat.'

All of this really sounds so much better than what it really is. It's murdering people all around the world, many of whom are 100% innocent. For instance the last person we droned in occupied Afghanistan was Zemari Ahmadi - a longtime worker for a US humanitarian aid organization. A US drone operator mistook bottles of water he was loading into his car for his family as bombs, and so they murdered him as well as 10 other civilians, including 7 children, all with the press of a button. [1]

[1] - https://www.nytimes.com/2021/09/10/world/asia/us-air-strike-...

owlbite · 2 months ago
But it can be even worse than that. It's "we assassinated the phone", "algorithm says vehicle has suspicious travel history and must die". There's no real thinking human in the loop for some of this stuff, just some model decided the metadata has a high probability of being associate with an opponent of some flavor and then everyone in the vicinity is blown to bits as computer said kill.
owlbite commented on Introducing architecture variants   discourse.ubuntu.com/t/in... · Posted by u/jnsgruk
colechristensen · 2 months ago
Most of the scientific numerical code I ever used had been in use for decades and would compile on a unix variant released in 1992, much less the distribution version of dependencies that were a year or two behind upstream.
owlbite · 2 months ago
Very true, but a lot of stuff builds on a few core optimized libraries like BLAS/LAPACK, and picking up a build of those targeted at a modern microarchitecture can give you 10x or more compared to a non-targeted build.

That said, most of those packages will just read the hardware capability from the OS and dispatch an appropriate codepath anyway. You maybe save some code footprint by restricting the number of codepaths it needs to compile.

owlbite commented on Computer science courses that don't exist, but should (2015)   prog21.dadgum.com/210.htm... · Posted by u/wonger_
LPisGood · 2 months ago
People don’t get this up in arms when there is a math course about using math tools or math history or how math is used to solve actual problems, but for some reason they do about computer science.
owlbite · 2 months ago
They just label such people as Applied Mathematicians, or worse: Physicists and Engineers; and then get back to sensible business such as algebraic geometry, complex analysis and group theory.
owlbite commented on Computer science courses that don't exist, but should (2015)   prog21.dadgum.com/210.htm... · Posted by u/wonger_
aryehof · 2 months ago
CS102 Big Balls of Mud: Data buckets, functions, modules and namespaces

CS103 Methodologies: Advanced Hack at it ‘till it Works

CS103 History: Fashion, Buzzwords and Reinvention

CS104 AI teaches Software Architecture (CS103 prerequisite)

owlbite · 2 months ago
Introduction to PhD study: "How hard can it be, I'm sure I could write that in a week"
owlbite commented on The reason GCC is not a library (2000)   gcc.gnu.org/legacy-ml/gcc... · Posted by u/todsacerdoti
tehjoker · 2 months ago
For what it's worth, the leverage did work, just not forever. It was a play with a limited lifetime. It didn't necessarily need to shake out that way, probably if GCC was slightly easier to write for but not too easy people would have invested more. It took a major investment to create a competing product.
owlbite · 2 months ago
I thought GPLv3 adoption by GCC was what really lit the flames on moving to llvm by commercial entities?
owlbite commented on Matrices can be your friends (2002)   sjbaker.org/steve/omniv/m... · Posted by u/todsacerdoti
bee_rider · 2 months ago
The MKL blas/lapack implementation also provides the “cblas” interface (I’m sure most blas implementations do, I’m just familiar with MKL—BLIS seems quite willing to provide additional interfaces to I bet they provide it as well) which explicitly accepts arguments for row or column ordering.

Internally the matrix is tiled out anyway (for gemm at least) so column vs row ordering is probably a little less important nowadays (which isn’t to say it never matters).

owlbite · 2 months ago
Oh yes, from an actual implementation POV you can just apply some transpose and ordering transforms to convert from row major to column major or vice-versa. cblas is pretty universal though I don't think any LAPACK C API ever gained as wide support for non column-major usage (and actually has some routines where you can't just pull transpose tricks for the transformation).

Certain layouts have performance advantages for certain operations on certain microarchitectures due to data access patterns (especially for level 2 BLAS), but that's largely irrelevant to historical discussion of the API's evolution.

owlbite commented on Matrices can be your friends (2002)   sjbaker.org/steve/omniv/m... · Posted by u/todsacerdoti
Viliam1234 · 2 months ago
> Mathematicians like to see their matrices laid out on paper this way (with the array indices increasing down the columns instead of across the rows as a programmer would usually write them).

Could a mathematician please confirm of disconfirm this?

I think that different branches of mathematics have different rules about this, which is why careful writers make it explicit.

owlbite · 2 months ago
What I suspect he really means is that FORTRAN lays out its arrays column-major, whilst C choose row-major. Historically most math software was written in the former, including the de facto standard BLAS and LAPACK APIs used for most linear algebra. Mix-and-matching memory layouts is a recipe for confusion and bugs, so "mathematicians" (which I'll read as people writing a lot of non-ML matrix-related code) tend to prefer to stick with column major.

Of course things have moved on since then and a lot of software these days is written in languages that inherited their array ordering from C, leading to much fun and confusion.

The other gotcha with a lot of these APIs is of course 0 vs 1-based array numbering.

owlbite commented on Why we need SIMD   parallelprogrammer.substa... · Posted by u/atan2
vardump · 2 months ago
Wider SIMD would be useful, especially with AVX-512 style improvements. 1024 or even 2048 bits wide operations.

Of course memory bandwidth should increase proportionally otherwise the cores might have no data to process.

owlbite · 2 months ago
Much better to burn the area for multiple smaller units, its a bit more area for frontend handling, but worth it for the flexibility (see Apple's M-series chips vs intel avx*).
owlbite commented on Restrictions on house sharing by unrelated roommates   marginalrevolution.com/ma... · Posted by u/surprisetalk
cjs_ac · 3 months ago
In the 1970s, it was usual for working class newlyweds would have to live with their parents until they were able to find housing. That's why second-rate comedians of the time like Les Dawson had so many mother-in-law jokes: there was an awful lot of resentment between young men and their mothers-in-law to exploit. There's nothing new about multiple families crowding into houses designed for just one family in this country - that's why there are so many pubs.

The Town and Country Planning Act 1947 has been identified as a cause of insufficient housebuilding activity, and new legislation is currently working its way through the House of Lords to alleviate this.

owlbite · 3 months ago
In the UK specifically the radical reform (read destruction) of council housing by the Thatcher government had a large impact on the housing market in the 1980s.

u/owlbite

KarmaCake day505April 21, 2021View Original