Struct bacon_sci::ivp::BDF2

pub struct BDF2<N, const S: usize>where
    N: ComplexField + FromPrimitive,
    <N as ComplexField>::RealField: FromPrimitive,
    Const<S>: DimMin<Const<S>, Output = Const<S>>,{ /* private fields */ }

2nd order backwards differentiation formula method for solving an initial value problem.

Defines the higher and lower order coefficients. Uses BDFInfo for the actual solving.

Examples

use nalgebra::SVector;
use bacon_sci::ivp::{BDF2, BDFSolver};
fn derivatives(_t: f64, state: &[f64], _p: &mut ()) -> Result<SVector<f64, 1>, String> {
    Ok(-SVector::<f64, 1>::from_column_slice(state))
}

fn example() -> Result<(), String> {
    let bdf = BDF2::new()
        .with_dt_max(0.1)?
        .with_dt_min(0.00001)?
        .with_tolerance(0.00001)?
        .with_start(0.0)?
        .with_end(10.0)?
        .with_initial_conditions(&[1.0])?
        .build();
    let path = bdf.solve_ivp(derivatives, &mut ())?;
    for (time, state) in &path {
        assert!(((-time).exp() - state.column(0)[0]).abs() < 0.001);
    }
    Ok(())
}

Implementations

impl<N, const S: usize> BDF2<N, S>where N: ComplexField + FromPrimitive + Copy, <N as ComplexField>::RealField: FromPrimitive + Copy, Const<S>: DimMin<Const<S>, Output = Const<S>>,

pub fn new() -> Self

Trait Implementations

impl<N, const S: usize> BDFSolver<N, S, 3> for BDF2<N, S>where N: ComplexField + FromPrimitive + Copy, <N as ComplexField>::RealField: FromPrimitive + Copy, Const<S>: DimMin<Const<S>, Output = Const<S>>,

fn higher_coefficients() -> SVector<N::RealField, 3>

The polynomial interpolation coefficients for the higher-order method. Should start with the coefficient for the derivative function without h, then n - 1. The coefficients for the previous terms should have the sign as if they’re on the same side of the = as the next state.

fn lower_coefficients() -> SVector<N::RealField, 3>

The polynomial interpolation coefficients for the lower-order method. Must be one less in length than higher_coefficients. Should start with the coefficient for the derivative function without h, then n-1. The coefficients for the previous terms should have the sign as if they’re on the same side of the = as the next state.

fn solve_ivp<T, F>( self, f: F, params: &mut T ) -> Result<Vec<(N::RealField, SVector<N, S>)>, String>where T: Clone, F: FnMut(N::RealField, &[N], &mut T) -> Result<SVector<N, S>, String>,

Use BDFInfo to solve an initial value problem

fn with_tolerance(self, tol: N::RealField) -> Result<Self, String>

Set the error tolerance for this solver.

fn with_dt_max(self, max: N::RealField) -> Result<Self, String>

Set the maximum time step for this solver.

fn with_dt_min(self, min: N::RealField) -> Result<Self, String>

Set the minimum time step for this solver.

fn with_start(self, t_initial: N::RealField) -> Result<Self, String>

Set the initial time for this solver.

fn with_end(self, t_final: N::RealField) -> Result<Self, String>

Set the end time for this solver.

fn with_initial_conditions(self, start: &[N]) -> Result<Self, String>

Set the initial conditions for this solver.

fn build(self) -> Self

Build this solver.

impl<N, const S: usize> Clone for BDF2<N, S>where N: ComplexField + FromPrimitive + Clone, <N as ComplexField>::RealField: FromPrimitive, Const<S>: DimMin<Const<S>, Output = Const<S>>,

fn clone(&self) -> BDF2<N, S>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<N, const S: usize> Debug for BDF2<N, S>where N: ComplexField + FromPrimitive + Debug, <N as ComplexField>::RealField: FromPrimitive, Const<S>: DimMin<Const<S>, Output = Const<S>>,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<N, const S: usize> Default for BDF2<N, S>where N: ComplexField + FromPrimitive + Copy, <N as ComplexField>::RealField: FromPrimitive + Copy, Const<S>: DimMin<Const<S>, Output = Const<S>>,

fn default() -> Self

Returns the “default value” for a type.

impl<N, const S: usize> From<BDF2<N, S>> for BDFInfo<N, S, 3>where N: ComplexField + FromPrimitive, <N as ComplexField>::RealField: FromPrimitive, Const<S>: DimMin<Const<S>, Output = Const<S>>,

fn from(bdf: BDF2<N, S>) -> BDFInfo<N, S, 3>

Converts to this type from the input type.