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Merged
prehner merged 1 commit into from
Jul 24, 2026
Merged

Clean the implementation of temperature_or_pressure arguments somewhat #369

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4 changes: 4 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [Breaking]
### Changed
- Changed data type of initial temperatures or pressure for phase equilibrium calculations (`TemperatureOrPressure::Other`) from `D` to `f64`. [#369](https://github.com/feos-org/feos/pull/369)

## [Unreleased]

## [0.10.0] - 2026-07-15
Expand Down
206 changes: 94 additions & 112 deletions crates/feos-core/src/phase_equilibria/bubble_dew.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,10 +31,7 @@ pub trait TemperatureOrPressure<D: DualNum<f64> + Copy = f64>: Copy {
fn temperature(&self) -> Option<Temperature<D>>;
fn pressure(&self) -> Option<Pressure<D>>;

fn temperature_pressure(
&self,
tp_init: Option<Self::Other>,
) -> (Option<Temperature<D>>, Option<Pressure<D>>, bool);
fn specification(&self, tp_init: Option<Self::Other>) -> TemperatureOrPressureSpecification<D>;

fn from_state<E: Residual<N, D>, N: Gradients>(state: &State<E, N, D>) -> Self::Other
where
Expand All @@ -50,7 +47,7 @@ pub trait TemperatureOrPressure<D: DualNum<f64> + Copy = f64>: Copy {
}

impl<D: DualNum<f64> + Copy> TemperatureOrPressure<D> for Temperature<D> {
type Other = Pressure<D>;
type Other = Pressure;
const IDENTIFIER: &'static str = "temperature";

fn temperature(&self) -> Option<Temperature<D>> {
Expand All @@ -61,30 +58,27 @@ impl<D: DualNum<f64> + Copy> TemperatureOrPressure<D> for Temperature<D> {
None
}

fn temperature_pressure(
&self,
tp_init: Option<Self::Other>,
) -> (Option<Temperature<D>>, Option<Pressure<D>>, bool) {
(Some(*self), tp_init, true)
fn specification(&self, tp_init: Option<Self::Other>) -> TemperatureOrPressureSpecification<D> {
TemperatureOrPressureSpecification::Temperature(*self, tp_init)
}

fn from_state<E: Residual<N, D>, N: Gradients>(state: &State<E, N, D>) -> Self::Other
where
DefaultAllocator: Allocator<N>,
{
state.pressure(Contributions::Total)
state.pressure(Contributions::Total).re()
}

#[cfg(feature = "ndarray")]
fn linspace(
&self,
start: Pressure<D>,
end: Pressure<D>,
start: Pressure,
end: Pressure,
n: usize,
) -> (Temperature<Array1<f64>>, Pressure<Array1<f64>>) {
(
Temperature::linspace(self.re(), self.re(), n),
Pressure::linspace(start.re(), end.re(), n),
Pressure::linspace(start, end, n),
)
}
}
Expand All @@ -95,7 +89,7 @@ impl<D: DualNum<f64> + Copy> TemperatureOrPressure<D> for Temperature<D> {
impl<D: DualNum<f64> + Copy> TemperatureOrPressure<D>
for Quantity<D, SIUnit<-2, -1, 1, 0, 0, 0, 0>>
{
type Other = Temperature<D>;
type Other = Temperature;
const IDENTIFIER: &'static str = "pressure";

fn temperature(&self) -> Option<Temperature<D>> {
Expand All @@ -106,34 +100,43 @@ impl<D: DualNum<f64> + Copy> TemperatureOrPressure<D>
Some(*self)
}

fn temperature_pressure(
&self,
tp_init: Option<Self::Other>,
) -> (Option<Temperature<D>>, Option<Pressure<D>>, bool) {
(tp_init, Some(*self), false)
fn specification(&self, tp_init: Option<Self::Other>) -> TemperatureOrPressureSpecification<D> {
TemperatureOrPressureSpecification::Pressure(*self, tp_init)
}

fn from_state<E: Residual<N, D>, N: Dim>(state: &State<E, N, D>) -> Self::Other
where
DefaultAllocator: Allocator<N>,
{
state.temperature
state.temperature.re()
}

#[cfg(feature = "ndarray")]
fn linspace(
&self,
start: Temperature<D>,
end: Temperature<D>,
start: Temperature,
end: Temperature,
n: usize,
) -> (Temperature<Array1<f64>>, Pressure<Array1<f64>>) {
(
Temperature::linspace(start.re(), end.re(), n),
Temperature::linspace(start, end, n),
Pressure::linspace(self.re(), self.re(), n),
)
}
}

/// Specification and initial value for a phase equilibrium calculation.
pub enum TemperatureOrPressureSpecification<D> {
Temperature(Temperature<D>, Option<Pressure>),
Pressure(Pressure<D>, Option<Temperature>),
}

impl<D> TemperatureOrPressureSpecification<D> {
fn is_temperature(&self) -> bool {
matches!(self, Self::Temperature(_, _))
}
}

/// # Bubble and dew point calculations
impl<E: Residual<N, D>, N: Gradients, D: DualNum<f64> + Copy> PhaseEquilibrium<E, 2, N, D>
where
Expand Down Expand Up @@ -197,134 +200,113 @@ where
}
Ok(vle)
} else {
let (temperature, pressure, iterate_p) =
temperature_or_pressure.temperature_pressure(tp_init);
Self::bubble_dew_point_tp(
eos,
temperature,
pressure,
temperature_or_pressure,
tp_init,
vapor_molefracs,
liquid_molefracs,
bubble,
iterate_p,
options,
)
}
}

#[expect(clippy::too_many_arguments)]
fn bubble_dew_point_tp<X: Composition<D, N>>(
fn bubble_dew_point_tp<TP: TemperatureOrPressure<D>, X: Composition<D, N>>(
eos: &E,
temperature: Option<Temperature<D>>,
pressure: Option<Pressure<D>>,
temperature_or_pressure: TP,
tp_init: Option<TP::Other>,
composition: X,
molefracs_init: Option<&OVector<f64, N>>,
bubble: bool,
iterate_p: bool,
options: (SolverOptions, SolverOptions),
) -> FeosResult<Self> {
let eos_re = eos.re();
let mut temperature_re = temperature.map(|t| t.re());
let mut pressure_re = pressure.map(|p| p.re());
let iterate_p = temperature_or_pressure
.specification(tp_init)
.is_temperature();
let (molefracs_spec, total_moles) = composition.into_molefracs(eos)?;
let molefracs_spec_re = molefracs_spec.map(|x| x.re());
let (v1, rho2) = if iterate_p {
// temperature is specified
let temperature_re = temperature_re.as_mut().ok_or(FeosError::Error(
"Temperature information is expected for bubble/dew calculation.".to_string(),
))?;

// First use given initial pressure if applicable
if let Some(p) = pressure_re.as_mut() {
PhaseEquilibrium::iterate_bubble_dew(
&eos_re,
temperature_re,
p,
&molefracs_spec_re,
molefracs_init,
bubble,
iterate_p,
options,
)?
} else {
// Next try to initialize with an ideal gas assumption
let x2 = PhaseEquilibrium::starting_pressure_ideal_gas(
&eos_re,
*temperature_re,
&molefracs_spec_re,
bubble,
)
.and_then(|(p, x)| {
let p = pressure_re.insert(p);
PhaseEquilibrium::iterate_bubble_dew(
let (mut t, mut p, v1, rho2) = match temperature_or_pressure.specification(tp_init) {
TemperatureOrPressureSpecification::Temperature(t, mut p) => {
// First use given initial pressure if applicable
let (p, v1, rho2) = if let Some(p) = p.as_mut() {
let (v1, rho2) = PhaseEquilibrium::iterate_bubble_dew(
&eos_re,
temperature_re,
&mut t.re(),
p,
&molefracs_spec_re,
molefracs_init.or(Some(&x)),
molefracs_init,
bubble,
iterate_p,
options,
)
});

// Finally use the spinodal to initialize the calculation
x2.or_else(|_| {
PhaseEquilibrium::starting_pressure_spinodal(
)?;
(*p, v1, rho2)
} else {
let x2 = PhaseEquilibrium::starting_pressure_ideal_gas(
&eos_re,
*temperature_re,
t.re(),
&molefracs_spec_re,
bubble,
)
.and_then(|p| {
let p = pressure_re.insert(p);
PhaseEquilibrium::iterate_bubble_dew(
.and_then(|(mut p, x)| {
let (v1, rho2) = PhaseEquilibrium::iterate_bubble_dew(
&eos_re,
temperature_re,
p,
&mut t.re(),
&mut p,
&molefracs_spec_re,
molefracs_init,
molefracs_init.or(Some(&x)),
bubble,
iterate_p,
options,
)?;
Ok((p, v1, rho2))
});

// Finally use the spinodal to initialize the calculation
x2.or_else(|_| {
PhaseEquilibrium::starting_pressure_spinodal(
&eos_re,
t.re(),
&molefracs_spec_re,
)
})
})?
.and_then(|mut p| {
let (v1, rho2) = PhaseEquilibrium::iterate_bubble_dew(
&eos_re,
&mut t.re(),
&mut p,
&molefracs_spec_re,
molefracs_init,
bubble,
iterate_p,
options,
)?;
Ok((p, v1, rho2))
})
})?
};
(t.into_reduced(), D::from(p.into_reduced()), v1, rho2)
}
} else {
// pressure is specified
let pressure_re = pressure_re.as_mut().ok_or(FeosError::Error(
"Pressure information is expected for bubble/dew calculation.".to_string(),
))?;

let temperature_re = temperature_re
.as_mut()
TemperatureOrPressureSpecification::Pressure(p, mut t) => {
let mut pressure_re = p.re();
let t = t.as_mut()
.ok_or(FeosError::Error(
"An initial temperature is required for the calculation of bubble/dew points at given pressure.".to_string()))?;
PhaseEquilibrium::iterate_bubble_dew(
&eos.re(),
temperature_re,
pressure_re,
&molefracs_spec_re,
molefracs_init,
bubble,
iterate_p,
options,
)?
let (v1, rho2) = PhaseEquilibrium::iterate_bubble_dew(
&eos.re(),
t,
&mut pressure_re,
&molefracs_spec_re,
molefracs_init,
bubble,
iterate_p,
options,
)?;
(D::from(t.into_reduced()), p.into_reduced(), v1, rho2)
}
};

// implicit differentiation
// unwraps here are safe
let (mut t, mut p) = if iterate_p {
(
temperature.unwrap().into_reduced(),
D::from(pressure_re.unwrap().into_reduced()),
)
} else {
(
D::from(temperature_re.unwrap().into_reduced()),
pressure.unwrap().into_reduced(),
)
};
let mut molar_volume = D::from(v1);
let mut rho2 = rho2.map(D::from);
for _ in 0..D::NDERIV {
Expand Down
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