Infinity
The two infinities are now valid values to be used as numeric limits. The infinity symbol (∞) is entered from the keyboard using the key combination Alt-f. The other infinity is obtained from the positive form by preceding it with a negative symbol (¯∞). The underbar symbol (_) is an alias for the infinity symbol on entry; however, when displaying the variable that contains an infinity, ∞ is used.
For example,
⌊/⍬
∞
⌈/⍬
¯∞
9*999
∞
÷0
∞
÷¯∞ ∞
0 0
¯_ _ ¯∞ ∞
¯∞ ∞ ¯∞ ∞
There are many cases that need to be examined to see how infinity should behave; this work has yet to be done, so you might notice some anomalous results using infinity.
Also, see the description of the system variable ⎕IC (Indeterminate Control) for a way to control how infinity along with other indeterminates are handled.