org.lsmp.djep.djep
Class DVariable

java.lang.Object
  java.util.Observable
      org.nfunk.jep.Variable
          org.lsmp.djep.xjep.XVariable
              org.lsmp.djep.djep.DVariable

Direct Known Subclasses:

MatrixVariable

public class DVariable
extends XVariable

Holds all info about a variable. Has a name, an equation, a dimension (or sent of dimensions if matrix or tensor) and also a set of PartialDerivative. The derivatives are stored in a hashtable index by the sorted names of derivatives. i.e. d^2f/dxdy, and d^2f/dydx will both be indexed by {"x","y"}. df/dx is indexed by {"x"}, d^2f/dx^2 is index by {"x","x"}. Partial derivatives are calculated as required by the findDerivative method.

Author:

Rich Morris Created on 26-Oct-2003

Field Summary

protected Hashtable

derivatives

Fields inherited from class org.nfunk.jep.Variable

name

Constructor Summary

protected	DVariable(String name) The constructor is package private.
protected	DVariable(String name, Object value)

Method Summary

Enumeration	allDerivatives() Enumerate all the derivatives of this variable.
protected PartialDerivative	createDerivative(String[] derivnames, Node eqn)
void	invalidateAll() makes value and values of all derivatives invalid.
static String	makeDerivString(String rootname, String[] dnames) Produces a string to represent the derivative.
void	setEquation(Node eqn) sets the equation
String	toString(PrintVisitor bpv) Returns a string rep of variable with its equation and value.

Methods inherited from class org.lsmp.djep.xjep.XVariable

calcValue, getEquation, hasEquation

Methods inherited from class org.nfunk.jep.Variable

getName, getValue, hasValidValue, isConstant, setIsConstant, setValidValue, setValue, setValueRaw, toString

Methods inherited from class java.util.Observable

addObserver, clearChanged, countObservers, deleteObserver, deleteObservers, hasChanged, notifyObservers, notifyObservers, setChanged

Methods inherited from class java.lang.Object

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

Field Detail

derivatives

protected Hashtable derivatives

Constructor Detail

DVariable

protected DVariable(String name)

The constructor is package private. Variables should be created using the VariableTable.find(Sting name) method.

DVariable

protected DVariable(String name,
                    Object value)

Method Detail

createDerivative

protected PartialDerivative createDerivative(String[] derivnames,
                                             Node eqn)

setEquation

public void setEquation(Node eqn)

sets the equation

Overrides:

setEquation in class XVariable

invalidateAll

public void invalidateAll()

makes value and values of all derivatives invalid.

makeDerivString

public static String makeDerivString(String rootname,
                                     String[] dnames)

Produces a string to represent the derivative. The string will be of the form "dx^2/dxdy". This string is used to index the derivatives of a variable.

Parameters:

rootname - name of the variable we are calculating the derivative of.

dnames - An array of the names of each of the partial derivatives.

Returns:

the string representation

toString

public String toString(PrintVisitor bpv)

Description copied from class: XVariable

Returns a string rep of variable with its equation and value.

Overrides:

toString in class XVariable

allDerivatives

public Enumeration allDerivatives()

Enumerate all the derivatives of this variable.

Returns:

an Enumeration running through all the derivatives.