public abstract class RungeKuttaIntegrator extends AbstractIntegrator
These methods are explicit RungeKutta methods, their Butcher arrays are as follows :
0  c2  a21 c3  a31 a32 ...  ... cs  as1 as2 ... ass1   b1 b2 ... bs1 bs
EulerIntegrator
,
ClassicalRungeKuttaIntegrator
,
GillIntegrator
,
MidpointIntegrator
isLastStep, resetOccurred, stepHandlers, stepSize, stepStart
Modifier  Constructor and Description 

protected 
RungeKuttaIntegrator(String name,
double[] c,
double[][] a,
double[] b,
org.apache.commons.math3.ode.nonstiff.RungeKuttaStepInterpolator prototype,
double step)
Simple constructor.

Modifier and Type  Method and Description 

void 
integrate(ExpandableStatefulODE equations,
double t)
Integrate a set of differential equations up to the given time.

double[] 
singleStep(FirstOrderDifferentialEquations equations,
double t0,
double[] y0,
double t)
Fast computation of a single step of ODE integration.

acceptStep, addEventHandler, addEventHandler, addStepHandler, clearEventHandlers, clearStepHandlers, computeDerivatives, getCurrentSignedStepsize, getCurrentStepStart, getEvaluations, getEvaluationsCounter, getEventHandlers, getExpandable, getMaxEvaluations, getName, getStepHandlers, initIntegration, integrate, sanityChecks, setEquations, setMaxEvaluations, setStateInitialized
protected RungeKuttaIntegrator(String name, double[] c, double[][] a, double[] b, org.apache.commons.math3.ode.nonstiff.RungeKuttaStepInterpolator prototype, double step)
name
 name of the methodc
 time steps from Butcher array (without the first zero)a
 internal weights from Butcher array (without the first empty row)b
 propagation weights for the high order method from Butcher arrayprototype
 prototype of the step interpolator to usestep
 integration steppublic void integrate(ExpandableStatefulODE equations, double t) throws NumberIsTooSmallException, DimensionMismatchException, MaxCountExceededException, NoBracketingException
This method solves an Initial Value Problem (IVP).
The set of differential equations is composed of a main set, which can be extended by some sets of secondary equations. The set of equations must be already set up with initial time and partial states. At integration completion, the final time and partial states will be available in the same object.
Since this method stores some internal state variables made
available in its public interface during integration (AbstractIntegrator.getCurrentSignedStepsize()
), it is not threadsafe.
integrate
in class AbstractIntegrator
equations
 complete set of differential equations to integratet
 target time for the integration
(can be set to a value smaller than t0
for backward integration)NumberIsTooSmallException
 if integration step is too smallDimensionMismatchException
 if the dimension of the complete state does not
match the complete equations sets dimensionMaxCountExceededException
 if the number of functions evaluations is exceededNoBracketingException
 if the location of an event cannot be bracketedpublic double[] singleStep(FirstOrderDifferentialEquations equations, double t0, double[] y0, double t)
This method is intended for the limited use case of very fast computation of only one step without using any of the rich features of general integrators that may take some time to set up (i.e. no step handlers, no events handlers, no additional states, no interpolators, no error control, no evaluations count, no sanity checks ...). It handles the strict minimum of computation, so it can be embedded in outer loops.
This method is not used at all by the integrate(ExpandableStatefulODE, double)
method. It also completely ignores the step set at construction time, and
uses only a single step to go from t0
to t
.
As this method does not use any of the statedependent features of the integrator, it should be reasonably threadsafe if and only if the provided differential equations are themselves threadsafe.
equations
 differential equations to integratet0
 initial timey0
 initial value of the state vector at t0t
 target time for the integration
(can be set to a value smaller than t0
for backward integration)t
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