Backslash Bar ⍀
Used as a Function
Monadic Backslash Bar is not defined
Dyadic Backslash Bar means Expand First
mat
1 2 3 4
5 6 7 8
9 10 11 12
1 0 2 1 ⍀ mat
1 2 3 4
0 0 0 0
5 6 7 8
5 6 7 8
9 10 11 12
Used as an Operator
Backslash Bar is a monadic operator with a dyadic operand
Operator Backslash Bar means Scan First
+⍀ mat
1 2 3 4
6 8 10 12
15 18 21 24