Code Golf: MSM Random Number Generator

Question

The challenge: The shortest code by character count that will generate a series of (pseudo)random numbers using the Middle-Square Method. The Middle-Square Method of (pseudo)random number generation was first suggested by John Von Neumann in 1946 and is defined as follows: Rn+1 = mid((Rn)2, m) For example: 34562 = 11943936 mid(11943936) = 9439 94392 = 89094721 mid(89094721) = 0947 9472 = 896809 mid(896809) = 9680 96802 = 93702400 mid(93702400) = 7024 Another example: 8432 = 710649 mid(710649) = 106 1062 = 11236 mid(11236) = 123 1232 = 15129 mid(15129) = 512 5122 = 262144 mid(262144) = 621 6212 = 385641 mid(385641) = 856 8562 = 732736 mid(732736) = 327 3272 = 106929 mid(106929) = 069 692 = 4761 mid(4761) = 476 4762 = 226576 mid(226576) = 265 Definition of `mid`: Apparently there is some confusion regarding the exact definition of `mid`. For the purposes of this challenge, assume that you are extracting the same number of digits as the starting seed. Meaning, if the starting seed had 4…

Accepted Answer

dc 26/37 chars

26 chars the function for a single number:

```
?dZsl2^dZ1+ll-2/Ar^/All^%p
```

37 chars with a 10 cycles loop:

```
?dZsl[2^dZ1+ll-2/Ar^/All^%pdzB>L]dsLx
```

Explanation of the function:

```
?            Input n
dZ           calculate number of digits
sl           store in register l
2^           calculate n^2
dZ           calculate number of digits of square
1+ll-2/Ar^/  n/(10^((squaredigits+1-l)/2)) int division truncates last digits 
All^%        n%(10^l) modulus truncates first digits
p            print the number
```

Test:

```
dc msml.dc
45678
86479
78617
80632
1519
30736
47016
10504
3340
11556
35411
```

Code Golf: MSM Random Number Generator

Solution

Problem