# Symbol Zilde

From NARS2000

Revision as of 08:20, 13 October 2019 by Paul Robinson (talk | contribs)

## ⍬ — Represents an **empty numeric vector** or *zero plus tilde* (hence zilde) — Keystroke Alt + Shift + } — Character ⎕UCS '⍬' = 9068

## Usage

⌊/⍬

∞

⌈/⍬

¯∞

Symbolically zero or **0** represents **number** while tilde or **∼** represents **not.** Together the overstrike zilde symbol or **⍬** means *not a number*, i.e. empty numeric vector. APL frequently uses overstrike characters in **dual-combined meaning,** thus **⍞** which is **⎕** or prompt and the single quote symbol yielding *prompt for string* or __character input__ **versus** **⎕** or prompt for __numeric input__.

## Example

The above examples for infinity and negative infinity correctly run in NARS2000. In **theory ONLY - ⍬** would be hypothetically equivalent to ⍳0 or 0⍴N (where N is any number) since zilde or ⍬ represents an empty numeric vector.