Skip to content

Documenting rounding issue in Binomial #24

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
May 27, 2025
Merged

Documenting rounding issue in Binomial #24

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
4c07d0f
document numeric issue in Binomial
benjamin-lieser May 22, 2025
bb51965
fmt
benjamin-lieser May 22, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 6 additions & 0 deletions src/binomial.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,12 @@ use rand::Rng;
/// let v = bin.sample(&mut rand::rng());
/// println!("{} is from a binomial distribution", v);
/// ```
///
/// # Numerics
/// The implementation uses `f64` internally, which leads to rounding errors for big numbers.
/// For very large samples (`> 2^53`) the least significant bits of the output will not be random.
/// This means that something like `bin.sample(&mut rand::rng()) % 4` will not follow the correct distribution.
/// The more significant bits should be correctly distributed.
#[derive(Clone, Copy, Debug, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct Binomial {
Expand Down