>>  <<  Usr  Pri  JfC  LJ  Phr  Dic  Rel  Voc  !:  Help  Dictionary

 Roll ?  0 0 0 Deal

 ? y yields a uniform random selection from the population i.y if y is a positive integer, or from the interval of numbers greater than 0 and less than 1 if y is 0. The random seed used begins at 7^5 (16807). x ? y is a list of x items randomly chosen without repetition from i.y .

```   ? 6
0

? 6 6 6 6 6 6 6 6
0 5 5 4 2 3 2 1

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

mean=: +/ % #
mean ? 1000 # 6
2.459

] m=: ? 4 4 \$ 9            NB. A random matrix for experimentation
3 8 8 4
2 0 2 7
4 2 3 5
1 1 7 2

-/ . * m                   NB. The determinant of m
_659

f=: ?@\$ % ] - 1:
3 6 f 9                    NB. Random 3 by 6 table in range zero to one with resolution 9
0.375     1     1  0.5  0.25     0
0.25 0.875   0.5 0.25 0.375 0.625
0.125 0.125 0.875 0.25 0.875  0.75

? 2 1 \$ !38x
202466594106002578660243928542852207957556146
79605116563118621090926071782092415123181713
```

Several instances of the foreign conjunction are provided to work with random numbers. 9!:(2*n) queries a parameter and 9!:(1+2*n) sets it.

9!:42 y
9!:43 y
RNG Select. Select the random number generator

 y RNG upper bound period period speed 1 GB_Flip 2^31 _1+2^55 3.60e16 1.0 2 Mersenne Twister 2^32 _1+2^19937 4.32e6001 1.1 3 DX-1597-4d _1+2^31 _1+(_1+2^31)^1597 1.24e14903 3.0 4 MRG32k3a _209+2^32 -:*/<:3^~_209 _22853+2^32 3.14e57 7.6 0 sum of above RNGs 11.8

“Speed” is the time for generating one million U(0,1) numbers, with 1.0 being the fastest. ? uses Mersenne Twister as the default RNG. ?. uses GB_Flip as the fixed RNG.

9!:44 y
9!:45 y
RNG State. The sequence of random numbers generated by an RNG depends completely on the state. The state is a boxed vector whose interpretation depends on the particular RNG. For example:
```   t=: 9!:44 ''  NB. query the RNG state
5 ?@\$ 10000
8590 6147 5158 4729 3522
2 4 ?@\$ 10
2 5 5 5
3 8 0 0
9!:45 t       NB. set the RNG state

5 ?@\$ 10000
8590 6147 5158 4729 3522
```
9!:0 y
9!:1 y
Random Seed. Queries and sets the random seed used in random number generation. The initial value is 7^5 . The seed may be a single integer or (for the Mersenne Twister RNG) a list of integers.

128!:4 y RNG Raw. Produces y integers as generated directly by an RNG, used typically for debugging the RNG.

>>  <<  Usr  Pri  JfC  LJ  Phr  Dic  Rel  Voc  !:  Help  Dictionary