Ciro Santilli (@cirosantilli) - New articles

Pre-shared key Updated 2025-07-16

An overview of what you can do with a pre-shared key with tradeoffs can be found at: quantumcomputing.stackexchange.com/questions/142/advantage-of-quantum-key-distribution-over-post-quantum-cryptography/25727#25727 The options are:

one-time pad
symmetric encryption
authentication with some message authentication code protocol

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Resource Description Framework Updated 2025-07-16

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This is one of those idealistic W3C specifications with super messy implementations all over.

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Rotate object around a point in Inkscape Updated 2025-07-16

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There's a tiny little crosshair that you can drag around to set the center of rotation.

And there's a button to make that crosshair snap: inkscape.org/forums/questions/can-a-pivotingtransfrom-crosshair-be-moved-and-made-to-snap-to-a-node-or-a-grid-point/#c14432

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Sponsor Ciro Santilli's work on OurBigBook.com / 1000 Monero donation Updated 2025-07-16

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The transaction ID was 5c6af4df39021f3a4a053ef169c9b397e6d6bf6c7e557d3f08e4e1675d7d3eed to self hist custody wallet with address 47kzoCeRMTohJhADejtsGmGimvQKzNsuST7u2aVhAD1VX5WDbh3v1FPUoJoTK3NTJVUgAM3dWCqC4Tmp9KSQaJi6GGYWgYn. This is a roof generated by his Monero wallet:

InProofV2AVFBmFhofH4GoG5NsaDutkdNWRTaEhuFgHpHTkpprRmuZ54B8FdUwFp71gqfp2jJpDUrhB3GCzZ2p8CNbh2TW1Z88ShmYWEwtkZFLccEMw9PhH3vWcMVo9mKaRsH3WgJXqq9

.

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Universal Module Definition Updated 2025-07-16

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Since JavaScript devs are incapable of defining an unified import standard, this design pattern emerged where you just check every magic global one by one. Here's a demo where a Js library works on both the browser and from Node.js:

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JavaScript library Updated 2025-08-08

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Assembly language Updated 2025-07-16

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A human readable way to write instructions for an instruction set architecture.

One of the topics covered in Ciro Santilli's Linux Kernel Module Cheat.

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less (Unix) Updated 2025-07-16

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Mathematical consistency of quantum field theory Updated 2025-07-16

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physics.stackexchange.com/questions/16142/is-qft-mathematically-self-consistent

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Solution of the Ising model Updated 2025-07-16

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TODO what it means to solve an Ising model in general?

stanford.edu/~jeffjar/statmech/lec4.html gives some good notions:

$< σ_{i} >$ is the expectation value of the value. It is therefore a number between -1.0 an and 1.0, -1.0 means everything is always down, 0.0 means half up half down, and 1.0 means all up
$< σ_{i} σ_{j} >$ : correlation between neighboring states. TODO.

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sudo Updated 2025-07-16

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Availability: unix.stackexchange.com/questions/48522/how-universal-is-sudo

xkcd.com/149/

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The Linux kernel responds to ICMP directly Updated 2025-07-16

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There is no userland process for it, it is handled directly by the Linux kernel: unix.stackexchange.com/questions/439801/what-linux-process-is-responsible-for-responding-to-pings/768739#768739

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Type-I superconductor Updated 2025-07-16

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Figure 1.
Sketch of the typical superconducting phase diagram of a Type-I superconductor
. Source.

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TypeScript Updated 2025-07-16

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TypeScript is good. It does find errors in your JavaScript. But it is a form of "turd polishing". But Ciro Santilli would rather have a polished turd than a non-polished one.

Part of the reason TypeScript became popular is due to the universality of asset bundlers. Once you are already using an asset bundler, changing the .js extension into .ts to get a less shitty experience is an easy choice.

The other big reason is that JavaScript is so lose with type conversions, notably undefined happily converting to strings without problems, and any missing properties of Object happily being undefined. We should actually use ES6 Map everywhere instead of using Objects as maps.

Since TypeScript is not the default form of the language however, it inevitably happens that you need to add external types for a gazillion projects that are using raw JavaScript, and sometimes fight a lot to get things to work. And so we have: github.com/DefinitelyTyped/DefinitelyTyped. Not sure if this is beautiful, or frightening.

But in the end, as with other type of static linters, TypeScript generally transforms a few hard to debug runtime issues, into a bunch of stupid to solve compile time issues, which is generally a good thing.

The fact that this it parses comments JSDoc comments in JavaScript files is quite amazing.

Examples under typescript. Run each one of them with:

npx tsc example.ts
node example.js

Helper:

tsr() (
  # ts Run
  f="$1"
  npx tsc "$f"
  node "${f%.*}.js"
)
tsr example.ts

typescript/inferFromInit.ts. Should fail with:
hello.ts:2:1 - error TS2322: Type 'string' is not assignable to type 'number
since TypeScript infers the type of i from first assignment as string, and we then attempt a number assignment later on
typescript/inferAfterInit.ts. Does not fail, as the first assignment cannot be computationally determined at runtime without breaking computer science.
typescript/js-from-ts/main.ts: call JavaScript file typescript/js-from-ts/notmain.js from TypeScript.
```
npx tsc jsFromTs.ts && node jsFromTs.js
```
TODO we are unable to make it typecheck that require, i.e. make that fail, but we've seen cases in complex codebases where that did happen and www.typescriptlang.org/docs/handbook/intro-to-js-ts.html has infinite information on supporting it. So... how to make it fail??
typescript/functionArgument.ts: basic argument tests
- typescript/functionOptionalArgument.ts: f(n?: number)
typescript/functionOptions.ts: f({n, s}: {n: number, s: string})