Pseudo-random numbers/PCG32: Difference between revisions
Add Rust implementation
(→{{header|C++}}: add header file <math.h> explicitly) |
(Add Rust implementation) |
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Line 1,925:
3215226955
{0=>20049, 1=>20022, 2=>20115, 3=>19809, 4=>20005}
</pre>
=={{header|Rust}}==
{{trans|C++}}
<syntaxhighlight lang="Rust">
struct PCG32 {
multiplier: u64,
state: u64,
inc: u64,
}
impl PCG32 {
fn new() -> Self {
PCG32 {
multiplier: 6364136223846793005,
state: 0x853c49e6748fea9b,
inc: 0xda3e39cb94b95bdb,
}
}
fn next_int(&mut self) -> u32 {
let old = self.state;
self.state = old.wrapping_mul(self.multiplier).wrapping_add(self.inc);
let xorshifted = (((old >> 18) ^ old) >> 27) as u32;
let rot = (old >> 59) as u32;
(xorshifted >> rot) | (xorshifted << ((!rot).wrapping_add(1) & 31))
}
fn next_float(&mut self) -> f64 {
(self.next_int() as f64) / ((1u64 << 32) as f64)
}
fn seed(&mut self, seed_state: u64, seed_sequence: u64) {
self.state = 0;
self.inc = (seed_sequence << 1) | 1;
self.next_int();
self.state = self.state.wrapping_add(seed_state);
self.next_int();
}
}
fn main() {
let mut rng = PCG32::new();
rng.seed(42, 54);
for _ in 0..5 {
println!("{}", rng.next_int());
}
println!();
let mut counts = [0; 5];
rng.seed(987654321, 1);
for _ in 0..100000 {
let j = (rng.next_float() * 5.0).floor() as usize;
counts[j] += 1;
}
println!("The counts for 100,000 repetitions are:");
for (i, count) in counts.iter().enumerate() {
println!(" {} : {}", i, count);
}
}
</syntaxhighlight>
{{out}}
<pre>
2707161783
2068313097
3122475824
2211639955
3215226955
The counts for 100,000 repetitions are:
0 : 20049
1 : 20022
2 : 20115
3 : 19809
4 : 20005
</pre>
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