Scalar extension: Difference between revisions

Scalar extension (view source)

32 bytes added , 14:54, 9 September 2022

Make clearer what's going on

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 === Rank extension ===
-The term "scalar extension" is sometimes used to refer to the practice of allowing a scalar when a higher rank is expected. The scalar is treated as an array of the expected minimum rank whose shape is a vector of 1s (that is, a [[singleton]]). For example, <source lang=apl inline>⍳8</source> and <source lang=apl inline>8⍴'a'</source> both produce an 8-element array even though the shape of an array is always a vector and so cannot be equal to <source lang=apl inline>8</source>. This type of extension, which differs from ordinary scalar extension in that there is no expected shape and only an expected rank, has also been present since [[APL\360]].
+The term "scalar extension" is sometimes used to refer to the practice of allowing a scalar when a higher rank is expected. The scalar is treated as an array of the expected minimum rank whose shape is a vector of 1s (that is, a [[singleton]]). For example, <source lang=apl inline>⍳8</source> and <source lang=apl inline>8⍴'a'</source> both produce an array of shape <source lang=apl inline>,8</source> (a vector) even though they were given a shape specification of  <source lang=apl inline>8</source> (a scalar). This type of extension, which differs from ordinary scalar extension in that there is no expected shape and only an expected rank, has also been present since [[APL\360]].
 === Singleton extension ===