Linear algebra
Linear algebra is one of the areas where the existing code has moved from BASE to STDLIB, so any work now needs to be prefaced with using linear algebra.
Linear algebra is a branch of mathematics concerning vector spaces and linear mappings between such spaces. It includes the study of lines, planes, and subspaces but is also concerned with properties common to all vector spaces and encompasses matrices and multidimensional arrays.
Julia has excellent support for the latter, mapping as it does higher-order arrays to 1D vectors, reinterpreted via a set of shape parameters. This means that an array, regardless of its arity, can be indexed as a 1D vector provided that that index does not exceed the total bounds of the array. It is worth noting also that for matrices, the apparent order is via columns, and for 3D arrays, from planes, then columns, and so on.
The normal rules for manipulating arrays are available in Julia, and we will not spend too much time on them...