doctor-syn

rationale

A computer algebra system for rust.

This crate is mostly for generating mathematical code at compile time. The focus is largely on numerical apprimation of transcendental and statistical functions to make them vectorisable.

For example, say we want to make an approximation to -cos(x*2π) over the domain -0.5..0.5, we can use the approx function to transform an expression.

fn gen_cos() -> proc_macro2::TokenStream {
    let xmin = -0.5;
    let xmax = 0.5;

    let approx = expr!((x * 3.1415926535897932384626433 * 2.0).cos() * -1.0)
        .approx(13, xmin, xmax, name!(x), Parity::Even)
        .unwrap()
        .use_suffix(Some("f32".to_string()))
        .unwrap()
        .into_inner();

    quote!(
        fn cos(x: f32) -> f32 {
            let x = x * (1.0 / (std::f32::consts::PI * 2.0));
            let x = x - x.floor() - 0.5;
            #approx
        }
    )
}

origin of the project name

Doctor Syn is the eponymous hero of the Russell Thorndike's novel and also a play on the syn rust library used to implement it.

https://en.wikipedia.org/wiki/Doctor_Syn

Doctor Syn was both a priest and a smuggler of the parish of Dymchurch on the Romney marshes.

libmgen

You can install the libmgen binary with:

cargo install --path . --bin libmgen

This can then be run as libmgen to generate a libm for various precisions, languages and data types.