libm VS clap-rs

Yes I took a look at build.rs. There's nothing here that stands out to me. Building the project on my Ubuntu machine works btw.

The more interesting code is the "kernel" tangent function https://github.com/rust-lang/libm/blob/master/src/math/k_tan.rs . I don't see any numerical analysis of accuracy in either the Rust lib or the MUSL source lib, but from one of the comments it looks like it's intended to be within 1ULP, which is what I'd expect.

It's nowhere near complete, but: https://github.com/rust-lang/libm

Inaccurate fast implementations use polynomial approximation. Accurate implementations use high-powered argument reduction and then polynomial approximation. Everything is polynomial approximation.

It looks like https://github.com/rust-lang/libm/pull/249 may be a fix for this.

In order to be standards-compliant, computer math libraries need to have a lot more digits of pi than should be strictly necessary. Accurately calculating sine in the upper reaches of double precision floats requires computer to have a table of about 100 digits of pi (or rather pi/2 for technically reasons) and 500 digits of 2/pi - here is an example.

So, fixed-point numbers weren't the solution to the problem either. The next thing I came across was the Rapier physics engine. It promises cross-platform determinism all IEEE 754-2008 compliant platforms. Although it's written in Rust, creating C# bindings was fairly easy, and I could use it in Unity after a few hours. But Rapier is still in early stages of development, which means that (at the time of writing this) it lacked many features, like raycasting, which would have been necessary for my project. Also, it's only deterministic on IEEE 754-2008 compliant platforms. But I couldn't really find any information on which processors support it. Even if I did, I still wanted to have deterministic physics on all platforms, not just on "most of them". But I still wondered does how Rapier achieve cross-platform floating point determinism. Supporting only IEEE 754-2008 compliant platforms is one thing, but the mathematical functions I mentioned above (sqrt, trigonometry, etc.) must also be deterministic. I found out that it uses libm, which implements all of these functions in software. It was primarily designed for embedded systems without FPUs, but it turns out it's also pretty useful for making this part of floating point math deterministic. But after all, the basic mathematical operations of floats are still not deterministic. Unless... How about emulating the behavior of floats in software? It should be possible to write a program that works on the byte representation of a float, doing all operations using integer arithmentic... right?

We will be using the library for Clap - A simple-to-use, efficient, and full-featured library for parsing command line arguments and subcommands.

I recently came across this question (and associated answer) on the clap repository. The answer given is a good one. But I wanted to expand with my own findings and practices, which spurred the motivation for this post.

We can also use tuple-like struct syntax and named-field struct syntax for enum variants within our enum; this is because unlike in other OOP languages, Rust enums are actually sum types. You can read more about how powerful Rust enums are in another article we wrote here. You can have optional arguments by simply wrapping the types in Option, but if you want to add a flag to a command you can use bool, since clap recognises that flags are either there or not there. Let's have a look at what this might look like:

I began by developing a wrapper for the CurseForge API, which turned out to be a lengthy and challenging process but constituted the bulk of the work. Next, I coded the CLI, which was relatively straightforward. Instead of using the clap crate, a Rust tool for generating CLIs, I opted for the following line of code:

By this time I had already gotten tired of parsing arguments by myself and had looked for something to help with that. I found a really dang good argument parsing library called clap. What makes it so cool is it's largely declarative for common uses. You simply mark up a struct with attributes, and the parser automatically generates the usage and all the argument parsing code.

How CLI arguments are handled (using clap).

Is this just referring to wrapping based on the terminal width? That is supported with the wrap_help feature though I have been considering making it a default feature.

CLI, use Clap. If you want to get fancy, use Tui.

As our CLI is getting more complex, we'll use the clap crate to parse the command line arguments.