Seven Obscure Languages in Seven Weeks

Adding More Array Operations

Two-dimensional matrices are special in science and technology. Unlike vectors alone, two-dimensional matrix equations are powerful to describe most processes that surround us (including infection diffusion in social networks). Unlike three- and higher-dimensional arrays, they’re still easy to visualize and comprehend. Not surprisingly, APL provides special support for two-dimensional arrays.

Let’s revisit the reduction explained. In the case of a vector, the reduction function op/A applies the function op to all elements. In the case of a matrix, there are two ways to reduce: row-wise and column-wise. Unless the matrix is symmetric, the outcomes will differ, and they will differ even more in a three-or-more-dimensional ...