Decode: Difference between revisions

{{Built-in|Decode|⊥}}, also called '''Base''', is a [[dyadic]] [[primitive function]] which evaluates the right [[argument]] in terms of the radix system defined by the left argument. Some implementations add [[monadic]] usage to this function, where the left argument defaults to the [[scalar]] 2. Decode is the [[inverse]] of [[Encode]] <source lang=apl inline>⊤</source> with the same left argument X, when X is a non-[[scalar]] array and the right argument is a valid representation of a number in the radix system defined by X.

Decode has an important property with array [[index]]: Given an arbitrary array A with [[shape]] S, the index of an [[element]] in A can be decoded with S to obtain the corresponding index in the [[ravel]] of A. Decoding all indices given by [[Index Generator]] shows the ravel order of the elements of an array with the given shape. Note that <source lang=apl inline>⎕IO←0</source> is required for this to hold.