>> << Ndx Usr Pri Phr Dic Rel Voc !: wd Help Dictionary

Roll | ? ?. 0 0 0 | Deal

`? y` yields a uniform random selection from the population`i.y` .`` The random seed used begins at`7^5` (16807) and is unaffected by the use of`?.` . |  | `x ? y` is a list of`x` items randomly chosen without repetition from`i.y` .`` The corresponding use of`?.` does not affect the random seed.

Use of the fixed seed function`?.` makes examples reproducible:

       ?. 6
    0

       ?. 6 6 6 6 6 6 6 6
    0 4 2 3 1 0 4 4

       6 ?. 6                     A random permutation
    5 1 2 4 3 0

       mean=: +/ % #
       mean ?. 1000 # 6
    2.497

       m=: ?. 4 4 $ 9             A random matrix for experimentation
       m
    1 6 4 4
    1 0 6 6
    8 3 4 7
    0 0 4 6

       -/ . * m                   The determinant of m
    588

       f=: ?.@$ % ] - 1:
       <3 6 f 9                   Random 3 by 6 table in range zero to one with resolution 9
    +--------------------------------+
    |0.125 0.75 0.5   0.5 0.125     0|
    | 0.75 0.75   1 0.375   0.5 0.875|
    |    0    0 0.5  0.75     0 0.375|
    +--------------------------------+

The random seed (a beginning value for the pseudo-random number generator) is set by the foreign conjunction using`9!:1`,`` and queried with`9!:0` .

>> << Ndx Usr Pri Phr Dic Rel Voc !: wd Help Dictionary