Phrases/Indices as Base

(i,j,...) are indices of an item in array A;
r is the index of the same item in the ravel of A (,A).
Then (i,j,...) = (($A) #: r).

Example: find indices of min:

   ]A=: _1(<1 2)}i.3 4
0 1  2  3
4 5 _1  7
8 9 10 11

   ($ #: (i. <./)@,) A
1 2

   ($ #: (i. <./)@,) _1(<2 1 4)}i.3 4 5
2 1 4

References

... are called for here.