IMimurray·Nov 4, 2023
I don't know APL, but from what I found quickly, APL's "conformability" rules[1] only seem to be a subset of the Yorick/NumPy broadcasting? Here's a Python example of broadcasting that APL doesn't seem to support(?): subtracting arrays of shape (3,1,7,5) and (1,4,1,5) to get an array of shape (3,4,7,5).
from numpy.random import randn
randn(3,1,7,5) - randn(1,4,1,5)
Inspired by other comments in this thread: The second line can also be run in current versions of Octave/Matlab as-is, BUT they didn't support it before NumPy, and neither did/does FORTRAN[2]. Mathworks resisted introducing this general form of broadcasting into Matlab for a long time. Octave then did it anyway (version 3.6.0 in 2012), and Matlab eventually followed (version R2016b). Before late 2016, Matlab code required `bsxfun(@minus, A, B)` instead of `A-B` to get
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broadcasting, and before bsxfun (introduced in R2007a) it was even more awkward (code often used `repmat`, or indexing tricks to explicitly expand arrays in memory to match shape).
[1] https://aplwiki.com/wiki/Conformability
[2] suggestion from 2022 to introduce broadcasting to Fortran: https://github.com/j3-fortran/fortran_proposals/issues/252