WebAssembly and embedded targets

Linear algebra can of course be dramatically useful for browser applications or embedded applications. For example, vector, matrix, and geometric operations are must-haves for any game running on the browser. Also, you may need matrix decompositions to perform machine-learning related data analysis on an embedded program. Luckily nalgebra supports both compiling for wasm and deactivating its link to the Rust standard library so that it becomes compilable for targets without libstd.

For browser applications#

All features of the nalgebra crate, including pure-rust implementations of matrix decompositions, will work out-of-the-box when compiled for the wasm32-unknown-unknown target. Recall that compiling to wasm only amounts to setting-up the target and passing the right parameters to cargo:

$ rustup target add wasm32-unknown-unknown # Must be done only once on your machine.
$ cargo build --target wasm32-unknown-unknown

On the other hand the nalgebra-lapack crate will not compile for wasm at all since it relies on binding to implementations of Blas and Lapack.

For embedded development#

When developing applications targeting embedded platforms, the rust standard library libstd is not always available. In those situations you typically have to add the #![no-std] attribute to your project to prevent it from linking to libstd. Though this will be useless if nalgebra itself links to the standard library! This section explains how to compile nalgebra without needing libstd, and how this affects the features you can use.

Note that the nalgebra-lapack crate on the other hand does not support being compiled without the Rust standard library yet.

Compiling without standard library#


Compiling without the standard library is necessary only for embedded development. You do not need to disable libstd when compiling to wasm!

nalgebra supports the std feature which is enabled by default. Disabling this feature will prevent nalgebra itself from linking to libstd. To achieve this you have to compile with a nightly version of the Rust compiler and declare your nalgebra dependency with default-features = false, i.e., like the following:

# Replace the * by the latest version number.
nalgebra = { version = "*", default-features = false }

This will affect what feature can be used. In particular:

  • All vector and matrix operations on statically-sized matrices and statically-sized vectors will continue work out-of-the box. Of course, this includes all the matrix decompositions!
  • Geometric operations will continue to work if the libm feature of nalgebra is enabled:
# Replace the * by the latest version number.
nalgebra = { version = "*", default-features = false, features = [ "libm" ] }
  • Creating random matrices or vectors without an user-provided distribution will not be available. Therefore the ::new_random() constructor will not exist. You may still use ::from_distribution(...) instead.
  • Dynamically sized vectors DVector and dynamically sized matrices DMatrix will not be available unless you activate the alloc feature as well and provide an allocator for your platform. This will let nalgebra link to the alloc crate and use the Vec data structure internally. You may do the following to enable this feature:
# Replace the * by the latest version number.
nalgebra = { version = "*", default-features = false, features = [ "alloc" ] }