* fix: #2990 DenseMatrix can mutate input arrays
* chore: simplify internal function `preprocess`
* chore: document ugly workaround of using `matrix.subset` to mutate a nested Array
* chore: better solution for `assign`
* chore: fix linting issue
* chore: add a unit test for `multiply` testing whether the operation is immutable
* chore: fix linting issue
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Co-authored-by: Glen Whitney <glen@studioinfinity.org>