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@rwxrwxrwx@mathstodon.xyz

I crunch numbers for a living.

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rwxrwxrwx, to math
@rwxrwxrwx@mathstodon.xyz avatar

Variations on a theme:

"The world is continuous, but the mind is discrete." —David Mumford (as cited in https://matthbeck.github.io/ccd.html)

gutenberg_org, (edited ) to books
@gutenberg_org@mastodon.social avatar

Spanish dramatis, writer and poet Pedro Calderón de la Barca died #OTD in 1681.

His plays have been divided thematically: religious comedies (La devoción de la cruz), historical-legendary (El sitio de Breda), comedies of intrigue (Casa con dos puertas, mala es de guardar), comedies of honor (El médico de su honra), philosophical (El gran teatro del mundo), mythological (Eco y Narciso) and sacramental acts (A Dios por razón de estado).

https://www.gutenberg.org/ebooks/author/970

#books

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@gutenberg_org Thanks for posting this. I really enjoy your OTD posts.

Just FYI, the translation of "autos sacramentales" is "sacramental acts" (see, for instance, https://en.wikipedia.org/wiki/Autos_sacramentales).

johncarlosbaez, to random
@johncarlosbaez@mathstodon.xyz avatar

Is there a chance that the physicist Oliver Heaviside was really Wolverine?

image/jpeg

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@johncarlosbaez @TruthSandwich Are you saying that Dirac's work was derivative of Heaviside's? δ(z) = H'(z) 🥁😆

rwxrwxrwx, to math
@rwxrwxrwx@mathstodon.xyz avatar

From the introduction of [1]:

"Our principal ambition for this paper is to make invitations to pure mathematicians to consider deploying constraint logic programming systems to assist in research, and to enthusiasts of the logic programming paradigm to consider applying their skills to problems in Lie theory. To this end we narrate a recent adventure searching for new simple Lie algebras over the field F2 = GF(2) of two elements in dialogue with the Prolog programming environment"

[1] D. Cushing, G. Stagg, and D. Stewart, “A Prolog assisted search for new simple Lie algebras,” Math. Comp., vol. 93, no. 347, pp. 1473–1495, May 2024, https://www.ams.org/journals/mcom/2024-93-347/S0025-5718-2023-03889-3/home.html

#prolog #math

foone, (edited ) to random
@foone@digipres.club avatar

I've no longer got a job, and I'm also kinda completely broke.

So if anyone has a few extra dollars they can donate to help me, that'd be very appreciated.

https://ko-fi.com/fooneturing

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@foone I'm glad to be able to send you a floppy disk. Take care.

https://Ko-fi.com/home/coffeeshop?txid=de6dbf07-9b00-4878-afb2-2e3f919cc251&mode=public&img=ogiboughtsomeone

masonporter, to random
@masonporter@mastodon.social avatar

This evening, I have written my parody of "One Way Or Another" (by Blondie) about trying to solve a partial differential equation (PDE).

In this parody, the person who is trying to solve the PDE gets increasingly desperate as the song goes on.

The inspiration is that whenever one of my students in a meeting (as occurred a few days ago) says something like "One way or another, I'm going to solve it.", my mind reacts immediately with "I'm gonna solve it, solve it, solve it, solve it."

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@masonporter It's hard to find words that rhyme with Courant-Friedrichs-Lewy.

jessica, to random
@jessica@mastodon.heavymusic.rocks avatar

Hi all y’all. I’m still binging Sisters of Mercy, send oxygen and food.

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@jessica Did you know these great renditions of unreleased Sisters songs? https://youtube.com/playlist?list=PLqB8OB5Sf6U7tN0Rn12EpdcG92wORx5n9&si=l98s1A-dWgv4jjJu

tqbf, to random

My brains are now leaking out of my ear holes, but we just finished an episode with Martin Albrecht sketching out the architecture of the best-known attacks on LWE PQ crypto. We asked ourselves, what would be the stuff Sean Devlin or Kelby Ludwig would want to know about how these attacks work (turns out: there's a lot conceptually in common with well-known attacks on conventional crypto), and then just Martin Albrecht is a fantastic explainer, even when he has to deal with me.

It ruled (for me at least) and I'm psyched.

rwxrwxrwx,
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@tqbf An episode? Where can one watch / listen to that?

TechConnectify, to random

It's not like I didn't know full well that it was gonna happen, but boy howdy is saying any nice thing about Large Internet Company on Mastodon quite the exercise.

I'm just another noodle on the internet - what do I know?

But perhaps if any mention of a mainstream anything invites You're Doing it Wrong and you Should Feel Bad About Your Opinions as responses by default... maybe this place isn't so fun.

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@TechConnectify FWIW, I appreciated reading your insights on YT.

Migueldeicaza, to random
@Migueldeicaza@mastodon.social avatar

Sharing this I saw on twitter by BrunoLevy01:

——

The simple #femtorv-quark takes no more than 200 lines of VERILOG. Yes, it is the complete description of a risc-v processor, that can run C programs compiled with gcc-riscv

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@Migueldeicaza FYI, @BrunoLevy01 is here

rygorous, to random
@rygorous@mastodon.gamedev.place avatar

There's a persistent misunderstanding that "smurfing" means playing a game you're already very experienced in from a new account. In reality, "smurfing" can mean absolutely anything, if you're a smurf.

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@pervognsen @rygorous I remember the Dolf arc as a kid. Good stuff!

dpiponi, to random
@dpiponi@mathstodon.xyz avatar

Unearthly

https://www.bbc.co.uk/news/science-environment-67063835

(Zoom in on the shell texture - it's pretty cool!)

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@pervognsen @dpiponi That horseshoe crab must have read Turing's work on morphogenesis.

ramin_hal9001, to cpp
@ramin_hal9001@emacs.ch avatar

C++ is everywhere, that makes ECL very valuable.

The software industry, especially in the realm of free software, has mostly settled on a pattern of using C++ for creating performance critical libraries, and creating Python binding to the C++ libraries for scripting. I was hoping Rust might come along and change all this, but it will take decades.

In the mean time, if you want to use C++ but not actually write C++, you can make use of the ECL Common Lisp compiler, which can compile Lisp to C++ code. This gives you all the best features of Common Lisp for programming with the universe of C++ code libraries available to you. You can use a C++ library and still have Common Lisp macros, garbage collection, high-level scripting, S-expressions as serialization, domain specific languages, a proper meta-object protocol that wraps C++ classes nicely, and wealth of choices for functional programming systems from the untyped lambda calculus all the way up the lambda cube to System-F and the Calculus of Constructs. This not only makes ECL a viable alternative to Python for scripting and app development, but objectively better than Python since you can actually turn your Common Lisp scripts into code that gets compiled into a larger C++ application.

With ECL I would have all sorts of C++ libraries available to me:

  • game engines like Unreal and Godot
  • 3D modeling: FreeCAD, OpenSCAD, Blender
  • Machine learning, big data, and HPC with PyTorch, TensorFlow, OpenCV, OpenCL

I will continue to contribute to the Scheme and Haskell communities as much as I can. I will continue to pursue my dream of an Xfce-like desktop environment written in Scheme. But no matter how I look at it, I am going to more productive in the long run using ECL and C++.

I was hoping that the software industry would gradually shift over to better, more functional languages like Rust and Haskell. And I would love it if Scheme languages could ever begin to seriously replace Python as a scripting language. But realistically, I think I am going to change tack and meet the industry half way. I think I should probably start using ECL as my language of choice, as much as I would prefer Scheme or an ML-family language like Haskell.

#Cpp #CommonLisp #ECL #cplusplus #python

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@ramin_hal9001 Have you tried CFFI's recent (and undocumented) C2FFI feature [1]? It can produce Common Lisp bindings automatically (using LLVM under the hood) for SBCL, ECL, CCL, etc.

Conversely, there's sbcl-librarian [2], which allows you to write dynamic libraries in SBCL that can be called from C, C++, etc.

[1] https://github.com/cffi/cffi#cffic2ffi

[2] https://github.com/quil-lang/sbcl-librarian

mcnees, to random
@mcnees@mastodon.social avatar

Mathematician Bernhard Riemann was born #OTD in 1826.

He made deep contributions to complex analysis and number theory, but physicists remember him for his work on the foundations of geometry. These insights provide the mathematical framework for general relativity.

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@mcnees This book, https://link.springer.com/book/10.1007/978-3-319-26042-6 , contains a translation of Riemann’s lecture as well as commentary relating it to modern differential geometry and its notation.

gvwilson, to random
@gvwilson@mastodon.social avatar

Do any of my friends have pointers to resources on statistical generation of synthetic data? Assume the reader/user is comfortable with Python and R but hasn't done a stats course in…a while. thanks

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@gvwilson Markov chain Monte Carlo or bootstrapping might help you, depending on what you have in mind.

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@gvwilson FWIW, TensorFlow Probability and PyMC both implement Markov chain Monte Carlo (although it's not hard to write your own) and have documentation available.

rwxrwxrwx, to random
@rwxrwxrwx@mathstodon.xyz avatar

The conjugate transpose of the Velázquez operator

#quantum

whitequark, to random
@whitequark@mastodon.social avatar

why is https://huggingface.co/ called that / why does it have that logo?

my brain parses it as acutely threatening and i just... try to not click links to it to avoid seeing the emoji

(edit: case in point, i have "show sensitive content" turned on and now it startles me every time i look at my own timeline. hoisted by my own petard, i guess)

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@whitequark I can't help but to immediately associate that company's name with the facehuggers from the Alien franchise. Surely I'm not the only one. https://alienanthology.fandom.com/wiki/Facehugger

rwxrwxrwx, to random
@rwxrwxrwx@mathstodon.xyz avatar

YouGlish is a remarkably good tool for those of us whose first language is not English: https://youglish.com/

You type a word and it plays clips of people on YouTube pronouncing that word. You can even narrow the results by country (UK, US, etc.).

Alas, it's of no use for figuring out the proper way to pronounce GIF 😅

louis, to random
@louis@emacs.ch avatar

TIL: Structures in #CommonLisp are implemented like vectors. Accessing elements is O(1) independent of the number of fields.

They could also be used a tuples. I would prefer structures over ALISTs or PLISTs, even Hashes when the data model is consistent.

Although many prefer CLOS classes over structures, I like their simplicity as a lightweight place for storing data.

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@louis I only recently learnt that you can use defstruct to create structures that are stored as lists (and vectors as well):

CL-USER> (defstruct (foo (:type list)) bar baz)
FOO
CL-USER> (make-foo :bar 1 :baz 2)
(1 2)
CL-USER> (foo-baz *)
2

johncarlosbaez, (edited ) to random
@johncarlosbaez@mathstodon.xyz avatar

Lorenz and Lorentz - two different physicists who did important work on similar subjects. It's easy to mix them up. Lots of textbooks call the Lorenz gauge the 'Lorentz gauge'. Let's stop doing that!

But what is the Lorenz gauge?

It's very efficient to describe the electromagnetic field using the 4-potential (A^\mu), which is a 1-form on spacetime. But you can change the 4-potential in certain ways without changing anything observable! This is called 'gauge symmetry'.

Gauge symmetry is important, but sometimes it's a bit of a nuisance. Sometimes it's nice to eliminate, or partially eliminate, this gauge symmetry by requiring that the 4-potential obeys various extra equations. These are called 'gauge conditions'.

Maxwell used a gauge condition now called 'Coulomb gauge'. To write this condition you need to choose a reference frame, so it goes against the spirit of special relativity - though it only affects unobservable quantities.

When Lorenz introduced his alternative gauge condition, Maxwell didn't like it - because he thought it would violate conservation of energy! But it's fine if we include the energy of the electromagnetic field, as we should. And it has the advantage of not requiring you to choose a reference frame, i.e. a notion of rest.

So yeah: the Lorenz gauge is Lorentz invariant.

To see how much confusion this has caused, read on!

(1/2)

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@j_bertolotti @johncarlosbaez Same thing with Laurent Schwartz (distributions) and Hermann Schwarz (Cauchy-Schwarz-... and Schwarz-Christoffel).

daviwil, to random
@daviwil@fosstodon.org avatar

You insert this floppy into your computer and switch to A:\

What do you find?

rwxrwxrwx,
@rwxrwxrwx@mathstodon.xyz avatar

@daviwil AUTOEXEC.BAT, CONFIG.SYS, and COMMAND.COM

Teri_Kanefield, to random

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    rwxrwxrwx,
    @rwxrwxrwx@mathstodon.xyz avatar

    @Teri_Kanefield I read this piece recently and I thought it made good points (it's mainly an explanation of the EEE argument): https://ploum.net/2023-06-23-how-to-kill-decentralised-networks.html

    xgranade, (edited ) to quantumcomputing
    @xgranade@wandering.shop avatar

    New newsletter post: You Can't Program Quantum Computers With Python (Part II)

    Give it a read through at https://buttondown.email/xgranade/archive/you-cant-program-quantum-computers-with-python-8808/, or check out Part I at https://buttondown.email/xgranade/archive/you-cant-program-quantum-computers-with-python/!

    #QuantumComputing

    rwxrwxrwx,
    @rwxrwxrwx@mathstodon.xyz avatar

    @xgranade That's right. That's what Lisp is for 😃 https://github.com/quil-lang/quilc

    foone, to random
    @foone@digipres.club avatar

    deleted_by_author

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    rwxrwxrwx,
    @rwxrwxrwx@mathstodon.xyz avatar

    @foone I'm glad to be able to help. Congrats on the new job!

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