Did you not check out `nalgebra`?
Every matrix package I've seen so far in Rust turns off subscript checking with unsafe code.
[1] http://graphics.stanford.edu/courses/cs148-10-summer/algebra... [2] https://docs.rs/crate/nalgebra/0.10.1/source/src/linalg/deco...
The whole point of Rust is to put an end to that.