Class JxnODE

java.lang.Object

JxnODE

All Implemented Interfaces:

FirstOrderDifferentialEquations

public class JxnODE
extends Object
implements FirstOrderDifferentialEquations

Wrapper used to pass a system of first order ordinary differential equations (odes) to Commons Math algorithms. Computes the derivatives dy_i/dt defined in the String[] odes.

See CommonsMath_ODE_Lotka_Volterra~Test.jxn for an example.

Constructor Summary

Constructors

Constructor	Description
JxnODE(KmgFormelInterpreter fi, String[] odes)	Constructs a FirstOrderDifferentialEquations instance to be used by Commons Math algorithms.
JxnODE(KmgFormelInterpreter fi, String init, String[] odes, double[] parameters)	See JxnODE(KmgFormelInterpreter, java.lang.String, java.lang.String[], double[]).

Method Summary

Modifier and Type	Method	Description
void	computeDerivatives(double t, double[] y, double[] ydot)	Computes derivatives ydot from y and t (internally called by Commons Math algorithms).
int	getDimension()	Returns the number of states.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

JxnODE

public JxnODE(KmgFormelInterpreter fi,
              String[] odes)

Constructs a FirstOrderDifferentialEquations instance to be used by Commons Math algorithms.
Example:

    ode = @JxODE( $this, { "$y[0]*( a - b $y[1] );", "$y[1]*( d $y[0] - c );" } )
 

Parameters:

fi - instance of KmgFormelInterpreter on which the definitions in odes[...] are executed

odes - array of statement_sequences (one or more statements separated by ';'). The definitions in odes[...] must use double[] $y and $t to calculate the derivatives dy/dt. If the definition in odes[i] ends with ';', log output of intermediate steps is suppressed for the definition.

JxnODE

public JxnODE(KmgFormelInterpreter fi,
              String init,
              String[] odes,
              double[] parameters)

See JxnODE(KmgFormelInterpreter, java.lang.String, java.lang.String[], double[]).

Parameters:

init - statement_sequence (one or more statements separated by ';'). init is evaluated before evaluating odes and can use double[] $y and $t. If init ends with ';', log output is suppressed.

parameters - the values can be used in the init and odes definitions via the array variable $p[...]

Method Detail

getDimension

public int getDimension()

Returns the number of states.

Specified by:

getDimension in interface FirstOrderDifferentialEquations

computeDerivatives

public void computeDerivatives(double t,
                               double[] y,
                               double[] ydot)

Computes derivatives ydot from y and t (internally called by Commons Math algorithms).

Specified by:

computeDerivatives in interface FirstOrderDifferentialEquations

toString

public String toString()

Overrides:

toString in class Object