Viewing profile — thxg

The original Wordle came with a pre-baked ordered list of 2315 "secret" words, off which the daily secret word was looked up (I think based on local time). The list was right there…

Indeed those are the "big four" solver businesses in the West, and also probably the most reliably-good solvers. But by the time Gurobi withdrew from the benchmarks (a few weeks ag…

Regarding presolve: When they test their solver "with presolve", they use Gurobi 's presolve as a preprocessing step, then run their solver on the output. To be clear, this is perf…

I agree that their results are impressive. Just to be clear, however: 1. They compare their solver with a 1e-4 error tolerance to Gurobi with 1e-6. This may seem like a detail, but…

I think it's partially excusable. Most LP solvers target large-scale instances, but instances that still fit in RAM. Think single-digit millions of variables and constraints, maybe…

The article is very recent (September 2023 [1]), mentions that "rax is used to return integer values" in the SysV ABI (hence implicitly the 64-bit SysV ABI). Also confirmed in this…

This representation of jagged array is literally the "Compressed Sparse Row" (CSR) format for sparse matrices [1]: - a single array of floats with all the nonzero matrix entries, o…

Ligatures are an interesting contrast to Julia programmers' habit of using actual (non-Latin) Unicode characters in their code. It seemed to me that the use of Greek letters and sy…

MemComputing mainly present themselves as optimizers: Their machine can solve real optimization problems, in practice, today. This is very good because, through that lens, we can s…

The scientific article seems to be open access [1]. Before people draw links to recent large language model breakthroughs: Although they do use techniques from computational lingui…

The video link in the article works in Chrome but not Firefox mobile (for some reason I can't comprehend). Working link in case you are interested: https://www.youtube.com/watch?v=…

> The best-known algorithms for NP-complete problems are essentially searching for a solution from all possible answers. The traveling salesman problem on a graph of a few hundred …

OP crafts a bmp file in paint, which when renamed to `.bat` runs the command that opens a shell window (cute!). I don't have access to a Windows machine, but isn't it possible to a…

> Ah yes, portability. On Linux it can be argued that CLOCK_MONOTONIC_RAW should be used for durations. From the Linux man page: CLOCK_MONOTONIC_RAW (since Linux 2.6.28; Linux-spec…

> How does it deal with dust from a household environment? At 5:55 the interviewee claims that the high back pressure allows them to blow the air through IP68 filter material. It s…

Examples on Compiler Explorer: By default, GCC generates FMA instructions on Haswell and later: https://godbolt.org/z/GKb7G4nW9 but it does not with -std=c99 on the command line: h…

The bug is about two related floating-point concepts: contraction and excess precision. The C and C++ standards mandate that floating-point operations follow the IEEE-754 spec. For…

Indeed GCC does not enable -ffast-math by default. Unfortunately, -ffast-math and -funsafe-math-optimizations (despite the name) are not the only options that prevent bit-for-bit-r…

> It is pretty crazy imho that gcc defaults to using fma Yes! Different people can make different performance-vs-correctness trade-offs, but I also think reproducible-by-default wo…

Yes, and this is not just a theoretical concern: There was an article here [1] in 2021 claiming that Apple M1's FMA implementation had "flaws". There was actually no such flaw. Ins…

This needs a (2004). The article mostly targets the Intel Pentium 4. Many high-level tips still hold true (for example those that could apply to any programming language, like expr…

One slight variation on the getaddrinfo()/freeaddrinfo() approach is what (among many others) GMP [1] and its derivatives do: For every struct or custom type, you systematically ge…