i.  (Verb)

INTEGERS (1)  The shape of i.y is |y, and its atoms are the first */|y non-negative integers. For example:

	  i. 2 3		    i. 2 _3
0 1 2			    2 1 0
3 4 5			    5 4 3

	  i. ''	      i. 4	       i. _4
0			        0 1 2 3		   3 2 1 0

As shown in the examples, a negative element in y causes reversal of the atoms along the corresponding axis.

INDEX OF ( _ _ )  If rix is the rank of an item of x, then the shape of the result of x i.y is (–rix)}.$y. Each atom of the result is either #x or the index of the first occurrence among the items of x of the corresponding rix-cell of y. The comparison in x i.y is tolerant.