How to pair cells from two arrays¶

Dyadic rank specifies separate cell ranks for the left and right arguments:

Add a different scalar to each row¶

      100 200 300 (+⍤0 1) 3 4⍴⍳12
101 102 103 104
205 206 207 208
309 310 311 312

The left argument has rank-0 cells (scalars), the right has rank-1 cells (rows). The frames both have shape 3, so they pair up: 100 with row 1, 200 with row 2, 300 with row 3.

Add a vector to each row¶

      10 20 30 40 (+⍤1) 3 4⍴⍳12
11 22 33 44
15 26 37 48
19 30 41 52

Both sides use rank-1 cells. The left has an empty frame (one cell), so it pairs with every right cell (scalar extension at the frame level).

Frame agreement¶

Frames must either match or one must be empty (scalar-extended). A mismatch gives a LENGTH ERROR.