Skip to content

Also fix roundoff errors in PcSaftPure #394

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
prehner merged 1 commit into from
Oct 14, 2026
Merged

Also fix roundoff errors in PcSaftPure #394

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
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
2 changes: 1 addition & 1 deletion CHANGELOG.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
## [Unreleased]

### Fixed
- Fixed numerical roundoff errors in the analytic solution of association site fractions for asymmetric association schemes. [#393](https://github.com/feos-org/feos/pull/393)
- Fixed numerical roundoff errors in the analytic solution of association site fractions for asymmetric association schemes. [#393](https://github.com/feos-org/feos/pull/393),[#394](https://github.com/feos-org/feos/pull/394)

## [0.10.2] - 2026-10-12
### Fixed
Expand Down
11 changes: 9 additions & 2 deletions crates/feos/src/pcsaft/eos/pcsaft_pure.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -105,8 +105,15 @@ fn helmholtz_energy_density<D: DualNum<f64> + Copy>(
let rhob = nb * density;
let aux = (rhoa - rhob) * delta + 1.0;
let sqrt = (aux * aux + rhob * delta * 4.0).sqrt();
let xa = (sqrt + 1.0 + (rhob - rhoa) * delta).recip() * 2.0;
let xb = (sqrt + 1.0 - (rhob - rhoa) * delta).recip() * 2.0;
let (xa, xb) = if na > nb {
let xb = (sqrt + aux).recip() * 2.0;
let xa = (rhob * delta * xb + 1.0).recip();
(xa, xb)
} else {
let xa = (sqrt - aux + 2.0).recip() * 2.0;
let xb = (rhoa * delta * xa + 1.0).recip();
(xa, xb)
};
let assoc = rhoa * (xa.ln() - xa * 0.5 + 0.5) + rhob * (xb.ln() - xb * 0.5 + 0.5);

non_assoc + assoc
Expand Down
Loading