math.objects
Class Variable

java.lang.Object
  |
  +--math.objects.Expression
        |
        +--math.objects.Variable

All Implemented Interfaces:

java.lang.Comparable

public class Variable

extends Expression

implements java.lang.Comparable

The class Variable is used to create mathematical Variable objects. It extends the Expr class.

Since:

JDK1.1

Author:

Peter Staab

, Pete Fox , both for the Mathematical Visualization Project for the Department of Applied Mathematics, University of Colorado at Boulder

Constructor Summary

Variable(java.lang.String identity)
Creates an Variable object given one String argument.

Method Summary

int	compareTo(java.lang.Object obj) Overrides the compareTo method of the Comparable object This is used for the VariableSet.
Expression	differentiate(Variable var) A method that returns the derivative of the Variable object using the summation rule of differentiation
boolean	equals(Variable var) Overrides the equal() method of the Object class.
double	evaluate(VariableSet vars, double[] values) A method used to evaluate a Variable object given an ordered variable vector and a corresponding array of constant double values
Expression	evaluateVariables(VariableSet variables, double[] values) A method used to evaluate a Variable object containing multiple variables given only one variable name and one value
java.lang.String	getIdentity() Returns the Variable object's identity as a String object
void	setIdentity(java.lang.String ident) Alternate method to set the Variable object's identity to a String object
Expression	simplify() A method that returns a Expression representation of the Variable object with its onlyChild in a simplified form with redundant terms combined and terms multiplied by zero eliminated.
java.lang.String	toString() Overrides the toString() method of the Object class.

Methods inherited from class math.objects.Expression

evaluate, evaluate, evaluate, evaluate, evaluate

Methods inherited from class java.lang.Object

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

Constructor Detail

Variable

public Variable(java.lang.String identity)
         throws UnacceptableVariableException

Creates an Variable object given one String argument.

Throws:

UnacceptableVariableException - if variable is of an unacceptable form.

Method Detail

toString

public java.lang.String toString()

Overrides the toString() method of the Object class. This gives a string represenation of the Symbolic Object.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of the Variable Object

getIdentity

public java.lang.String getIdentity()

Returns the Variable object's identity as a String object

Returns:

the Variable object's identity as a String object

setIdentity

public void setIdentity(java.lang.String ident)

Alternate method to set the Variable object's identity to a String object

equals

public boolean equals(Variable var)

Overrides the equal() method of the Object class. This determines whether two Variable objects have the same identity

Returns:

a boolean equal to true if identities are equal a boolean equal to false if identities are not equal

evaluate

public double evaluate(VariableSet vars,
                       double[] values)
                throws java.lang.ArithmeticException,
                       IllegalEvaluationException,
                       VariableUndefinedException

A method used to evaluate a Variable object given an ordered variable vector and a corresponding array of constant double values

Specified by:

evaluate in class Expression

Parameters:

vars - the name of the VariableVector of Variables associated with the function.

Returns:

a double representing the value of the Expression for the entered value.

Throws:

VariableUndefinedException - for Variables not defined

java.lang.ArithmeticException - for NaN and Divide by Zero

IllegalEvaluationException - if an error occurs

Since:

JDK1.1

evaluateVariables

public Expression evaluateVariables(VariableSet variables,
                                    double[] values)
                             throws java.lang.ArithmeticException,
                                    IllegalEvaluationException

A method used to evaluate a Variable object containing multiple variables given only one variable name and one value

Specified by:

evaluateVariables in class Expression

Parameters:

variables - a VariableSet value

values - a double[] value

Returns:

a Expression object representing the given Expression with one of it's variables evaluated for the given value.

Throws:

IllegalEvaluationException - if the number of variables do not equal the number of values.

java.lang.ArithmeticException - for NaN and Divide by Zero

Since:

JDK1.1

differentiate

public Expression differentiate(Variable var)

A method that returns the derivative of the Variable object using the summation rule of differentiation

Specified by:

differentiate in class Expression

Parameters:

var - the variable of differentiation

Returns:

an Expression object containing value of one representing the derivative of the Variable object if the derivative is with respect to this Variable object.

simplify

public Expression simplify()

A method that returns a Expression representation of the Variable object with its onlyChild in a simplified form with redundant terms combined and terms multiplied by zero eliminated.

Specified by:

simplify in class Expression

Returns:

an Expression object in a simplified form

compareTo

public int compareTo(java.lang.Object obj)

Overrides the compareTo method of the Comparable object This is used for the VariableSet.

Specified by:

compareTo in interface java.lang.Comparable