Fixes #666

[bofh69]

Checklist

• I've added tests for all code changes and additions (where applicable)
• I've added a demonstration of the new feature to one or more examples
• I've updated the book to reflect my changes
• Usage of new public items is shown in the API docs

API changes

[azriel91]

Thanks!

[azriel91]

bors r+

[bors]

Build failed

• continuous-integration/travis-ci/push

[azriel91]

Seems like rustc 1.42.0-nightly (a9dd56ff9 2019-12-30) breaks on compiling maxtrixmultiply 0.2.3, which nalgebra 0.19.0 depends on.

error: array lengths can't depend on generic parameters
   --> /home/travis/.cargo/registry/src/github.tiyicn.workers.dev-1ecc6299db9ec823/matrixmultiply-0.2.3/src/dgemm_kernel.rs:786:44
    |
786 |     let mut ab: [[T; NR]; MR] = [[0.; NR]; MR];
    |                                            ^^

(Likely) related:

• Recent nightly doesn't support array length from indirectly referenced trait constant rust-lang/rust#67743 (direct issue).
• https://github.com/bluss/matrixmultiply
• https://github.com/bluss/matrixmultiply/blob/0.2.3/src/dgemm_kernel.rs#L784-L786
• rustc claims that "array lengths can't depend on generic parameters" for exactly one type of expression, while various other far more complex expressions involving const generics work perfectly rust-lang/rust#63249
• Array lengths don't support generic parameters. rust-lang/rust#43408
• ICE w/ const_generics when trying to use the size of an associated type size as an array length rust-lang/rust#67739

Note: It compiles fine on rustc 1.42.0-nightly (0de96d37f 2019-12-19)

[azriel91]

bors try

[bors]

try

Build succeeded

• continuous-integration/travis-ci/push

[azriel91]

bors r+

[bors]

Build succeeded

• continuous-integration/travis-ci/push