qualia_core_db/
ode_solver.rs

1//! Continuous Differential Constraint Solvers
2//! Pure Rust implementation of ODE/PDE solvers, replacing C-library dependencies (e.g., Sundials).
3
4/// A simple state vector representing continuous physical constraints
5pub struct PhysicalState {
6    pub time: f64,
7    pub values: Vec<f64>,
8}
9
10/// Runge-Kutta 4th Order ODE Solver
11/// Solves dy/dt = f(t, y)
12pub fn rk4_step<F>(state: &mut PhysicalState, step_size: f64, derivative: F)
13where
14    F: Fn(f64, &[f64]) -> Vec<f64>,
15{
16    let t = state.time;
17    let y = &state.values;
18    let n = y.len();
19
20    let k1 = derivative(t, y);
21
22    let mut y_k2 = vec![0.0; n];
23    for i in 0..n {
24        y_k2[i] = y[i] + 0.5 * step_size * k1[i];
25    }
26    let k2 = derivative(t + 0.5 * step_size, &y_k2);
27
28    let mut y_k3 = vec![0.0; n];
29    for i in 0..n {
30        y_k3[i] = y[i] + 0.5 * step_size * k2[i];
31    }
32    let k3 = derivative(t + 0.5 * step_size, &y_k3);
33
34    let mut y_k4 = vec![0.0; n];
35    for i in 0..n {
36        y_k4[i] = y[i] + step_size * k3[i];
37    }
38    let k4 = derivative(t + step_size, &y_k4);
39
40    for i in 0..n {
41        state.values[i] += (step_size / 6.0) * (k1[i] + 2.0 * k2[i] + 2.0 * k3[i] + k4[i]);
42    }
43    state.time += step_size;
44}
45
46/// Evaluates constraints over a temporal series using RK4
47pub fn evaluate_continuous_dynamics(
48    initial_state: PhysicalState,
49    steps: usize,
50    dt: f64,
51) -> PhysicalState {
52    let mut current_state = initial_state;
53    // Example: dy/dt = -0.5 * y (decay function)
54    let decay_func = |_t: f64, y: &[f64]| -> Vec<f64> { y.iter().map(|&val| -0.5 * val).collect() };
55
56    for _ in 0..steps {
57        rk4_step(&mut current_state, dt, &decay_func);
58    }
59    current_state
60}
qualia_core_db/ode_solver.rs

qualia_core_db/
ode_solver.rs
