Runge-Kutta-Cash-Karp (RK45) ODE integrator with adaptive step control. More...

#include <functional>
#include <vector>
#include "OdeSolverDetail.hpp"

Include dependency graph for OdeSolver.hpp:

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Namespaces
namespace	openswmm

namespace	openswmm::ode

Typedefs
using	openswmm::ode::DerivFunc = std::function<void(double x, const double* y, double* dydx)>
	Synchronous derivative evaluator for an n-equation ODE system.

using	openswmm::ode::BatchDerivFunc
	Synchronous derivative evaluator for a batch of two-state systems.

Functions
int	openswmm::ode::integrate (double *y, int n, double x1, double x2, double eps, double h1, const DerivFunc &derivs)
	Advance an ODE system with adaptive Cash-Karp RK45 steps.

template<typename F>
int	openswmm::ode::integrateCallable (double *y, int n, double x1, double x2, double eps, double h1, F &&derivs)
	Integrate with a concrete synchronous derivative callable.

int	openswmm::ode::integrate_batch_2eq (double y0, double y1, int n_sys, double x1, double x2, double eps, double h1, const BatchDerivFunc &derivs)
	Advance independent two-state systems with one explicit Euler step.

Variables
constexpr int	openswmm::ode::MAXSTP = 10000
	Maximum integration steps.

constexpr double	openswmm::ode::TINY = 1.0e-30
	Underflow protection.

constexpr double	openswmm::ode::SAFETY = 0.9
	Step adjustment safety factor.

constexpr double	openswmm::ode::PGROW = -0.2
	Exponent for step increase.

constexpr double	openswmm::ode::PSHRNK = -0.25
	Exponent for step decrease.

constexpr double	openswmm::ode::ERRCON = 1.89e-4
	= (5/SAFETY)^(1/PGROW)

constexpr int	openswmm::ode::ODE_OK = 0
	Success.

constexpr int	openswmm::ode::ODE_TOO_MANY = 1
	n > allocated max

constexpr int	openswmm::ode::ODE_UNDERFLOW = 2
	Step size underflowed.

constexpr int	openswmm::ode::ODE_MAX_STEPS = 3
	Exceeded MAXSTP.

Detailed Description

Runge-Kutta-Cash-Karp (RK45) ODE integrator with adaptive step control.

Numerically identical to legacy odesolve.c. Uses 5th-order Runge-Kutta with embedded 4th-order error estimate for automatic step size control.

Used by:

Groundwater two-zone model (2 ODEs per subcatchment)
Subcatchment runoff ponded-depth integration

Vectorization note: Each subcatchment's ODE system is independent. For batch integration over N subcatchments, call integrate() N times or use integrate_batch_2eq() for a single explicit Euler step over SoA state arrays; the batch helper does not use adaptive RK45.

Note: Legacy reference: src/legacy/engine/odesolve.c

Author: Caleb Buahin caleb.nosp@m..bua.nosp@m.hin@g.nosp@m.mail.nosp@m..com

License: Apache-2.0

Namespaces

Typedefs

Functions

Variables

Detailed Description