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Miraheze>Adám Brudzewsky |
Miraheze>Adám Brudzewsky No edit summary |
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{{Primitive|?|Roll}} is a [[monadic]] [[scalar function]] which returns random or pseudo-random numbers. Each [[scalar]] in the argument must be a | {{Primitive|?|Roll}} is a [[monadic]] [[scalar function]] which returns random or pseudo-random numbers. Each [[scalar]] in the argument must be a positive integer, <source lang=apl inline>n</source>, and Roll chooses one of the first <source lang=apl inline>n</source> [[Index|indices]]. Some dialects allow <source lang=apl inline>n</source> to be zero, in which case Roll chooses a floating-point number between 0 and 1. | ||
== Examples == | == Examples == | ||
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== Description == | == Description == | ||
Each [[scalar]] in the argument to Roll must be a | Each [[scalar]] in the argument to Roll must be a positive integer. | ||
The result of Roll on each number <source lang=apl inline>n</source> is either | The result of Roll on each number <source lang=apl inline>n</source> is either | ||
* One of the elements of <source lang=apl inline>⍳n</source> chosen uniformly at random; or | |||
* One of the elements of <source lang=apl inline>⍳n</source> chosen uniformly at random, | * A real number between 0 and 1 chosen uniformly at random, if <source lang=apl inline>n</source> is 0 and the dialect has this extension. | ||
Because [[Iota]] depends on [[index origin]], Roll depends on index origin unless every number in the argument is 0. | Because [[Iota]] depends on [[index origin]], Roll depends on index origin unless every number in the argument is 0. | ||
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=== Lessons === | === Lessons === | ||
[https://chat.stackexchange.com/transcript/52405?m=41303127#41303127 APL Cultivation] | * [https://chat.stackexchange.com/transcript/52405?m=41303127#41303127 APL Cultivation] | ||
* [https://nbviewer.jupyter.org/github/Dyalog/dyalog-jupyter-notebooks/blob/master/Random%20Numbers.ipynb Jupyter Notebook] | |||
=== Documentation === | === Documentation === | ||
[http://help.dyalog.com/latest/Content/Language/Primitive%20Functions/Roll.htm Dyalog] | * [http://help.dyalog.com/latest/Content/Language/Primitive%20Functions/Roll.htm Dyalog] | ||
[http://microapl.com/apl_help/ch_020_020_170.htm APLX] | * [http://microapl.com/apl_help/ch_020_020_170.htm APLX] | ||
* [https://www.jsoftware.com/help/dictionary/d640.htm J Dictionary], [https://code.jsoftware.com/wiki/Vocabulary/query J NuVoc] | |||