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rust-random / rand

A Rust library for random number generation.
https://crates.io/crates/rand
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Poisson distribution returns -1.0 for very small values of lambda #1428

Closed thomasalcock closed 2 months ago

thomasalcock commented 3 months ago

With rand_distr = "0.4.3" and rand = "0.8.5" I was able to sample -1.0 by providing small enough values of lambda.

use rand_distr::{Distribution,Poisson};
use rand::thread_rng;

fn main() {

    let poisson_dist: Poisson<f32> = Poisson::new(0.0000000002).unwrap();
    println!("{:?}", poisson_dist.sample(&mut thread_rng()));

    let poisson_dist: Poisson<f64> = Poisson::new(0.0000000000000000002).unwrap();
    println!("{:?}", poisson_dist.sample(&mut thread_rng()));

}
dhardy commented 2 months ago

I can reproduce the bug with the versions listed, but not with the latest alpha releases.

vks commented 2 months ago

For reference, this was fixed with #1284.

Am Mi., 10. Apr. 2024 um 17:44 Uhr schrieb Diggory Hardy < @.***>:

Closed #1428 https://github.com/rust-random/rand/issues/1428 as completed.

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