Hi,
Please ignore if I am incorrect, being new to APL. But perhaps my 'new eyes' spotted two minor errors in the ]HELP for some operators:
1. 'squad' help
]help ⌷
dyadic function: Z ← A ⌷ B (Index)
Let A=A1 A2 ... An, n ≥ 0. Then (A ⌷ B) is B[A1;A2;...An]
B←1 4 1 5 1 6 1 7
⍋x
1 3 5 7 2 4 6 8
{(⊂⍋⍵)⌷⍵}B
1 1 1 1 4 5 6 7
x[1 3 5 7 2 4 6 8]
1 1 1 1 4 5 6 7
B[1;3;5;7;2;4;6;8]
RANK ERROR
B[1;3;5;7;2;4;6;8]
^^
..should the notation in ]help ⌷ rather be
dyadic function: Z ← A ⌷ B (Index)
Let A=A1 A2 ... An, n ≥ 0. Then (A ⌷ B) is B[A1 A2 ...An]
Since the semicolon (;) in array notation is rather to specify a single item in a matrix, rather than space to give multiple indices in a vector?
2. iota help
]help ⍳
monadic function: Z ← ⍳ B (Index generator)
Vector of the first B integers (starting from 0 or 1, see ⎕IO)
dyadic function: Z ← A ⍳ B (Index of)
The location (index) of B in A; 1+⌈/⍳⍴L if not found
.. should read
... The location (index) of B in A; 1+⌈/⍳⍴B if not found
As 'B' is the meta-variable in the description, not L.
Thank you,
-Russ