Generally every APL vendor added extra features into their version of the language, sometimes to accommodate new hardware or environments, sometimes to enhance their competitive advantage.
Burroughs and one or another DEC APL used cute quad-something glyphs, mostly for their file system operations. Maybe it was early IBM APL2 which had the eigenvalue glyphs. Or possibly the paper was a proposal to add the eigenvalue functionality and glyphs to the language. On 20/07/2015, Jay Foad <[email protected]> wrote: > What's the paper? Does it say which APL they were using? > > On 19 July 2015 at 16:25, <[email protected]> wrote: > >> Hi Bug APL, >> >> I found a paper that computes eigenvalues using the following equation >> eig←{t[;⍒(t←⍂⍵)[0;]]} >> >> where ⍵ is a matrix of coefficients. >> >> It looks like the symbols are in the unicode standard, but I have never >> seen a definition before: >> ⍁ >> U+2341 >> ⌼ >> APL Functional Symbol Quad Slash >> ⍂ >> U+2342 >> ⍂ >> APL Functional Symbol Quad Backslash >> >
