Anonymous user
Subtractive generator: Difference between revisions
→{{header|Mathematica}}
(Added Wren) |
|||
Line 1,171:
</pre>
=={{header|Nim}}==
<lang nim>import deques, sequtils
template shfl(idx): untyped = (K*(idx+1)) mod I
func mutuallyprime(I, K: int16): bool{.compiletime.} =
## compile time check shuffling works properly
let
x = {1'i16..I}
s = x.toSeq
var r: set[int16]
for n in 0..<I:
r.incl(s[n.shfl])
r == x
func `%`(i: int, m: int): int = (if i < 0: i+m else: i)
## positive modulo, and we don't need to test if > m
## because (i-j) is always less than m
template next(state): untyped =
state.addLast((state[^I]-state[^J]) % M)
discard state.popFirst()
func seedGen[I, J, K, M: static int](seed: range[0..M-1]): Deque[int] =
var s = @[seed, 1]
for _ in 2..<I:
s.add (s[^2]-s[^1]) % M
#reorder and put into ring buffer
for i in 0..<I:
result.addLast(s[i.shfl])
#cycle through the next 165 values
for _ in 0..<3*I:
result.next
func initSubGen[I, J, K, M: static int](seed: range[0..M-1]): auto =
##check parameters at compile time
##seed will be checked to be in the range 0..M-1
static:
for x in [I, J, K, M]:
assert x > 0, "all params must be positive"
assert I > J, "I must be > J"
assert mutuallyprime(I, K), "I,K must be relatively prime"
var r = seedGen[I, J, K, M](seed)
result = proc(): int =
r.next
return r.peekLast
let subGen* = initSubGen[55, 24, 34, 1e9.int]
when isMainModule:
let rand = subGen(292929)
for _ in 1..3:
echo rand()</lang>
{{out}}
<pre>467478574
512932792
539453717</pre>
=={{header|OCaml}}==
| |||