edu.hws.jcm.data
Interface Expression

All Superinterfaces:

java.io.Serializable, Value

All Known Implementing Classes:

Constant, ExpressionInput.EI, ExpressionProgram

public interface Expression

extends Value

An Expression represents a mathematical expression such as "x+1" or "3" or "sin(x*ln(x)-3*abs(x/4))". An expression has a value, which can depend on the values of variables that occur in the expression. An expression can be differenetiated with respect to a variable. It has a print string representation. This interface is implemented by the classes Constant, Variable, and ExpressionProgram, for example. The Expression interface represents all the properties of expressions that you are likely to need to know about, unless you want to write a new kind of ExpressionCommand.

Method Summary

boolean	dependsOn(Variable x) Checks whether the expression has any dependence on the variable x.
Expression	derivative(Variable wrt) Return an Expression that represents the derivative of this expression with respect to the variable wrt.
double	getValueWithCases(Cases cases) Compute and return the value of this expression.
java.lang.String	toString() Get a print string representation of this expression.

Methods inherited from interface edu.hws.jcm.data.Value

getVal

Method Detail

getValueWithCases

public double getValueWithCases(Cases cases)

Compute and return the value of this expression. If cases is non-null, then data is stored in cases that can be used to check for possible discontinuities between one evaluation and the next. See the class Cases for more information.

derivative

public Expression derivative(Variable wrt)

Return an Expression that represents the derivative of this expression with respect to the variable wrt. (Note that if the expression contains other variables besides wrt, this is actually a partial derivative.)

dependsOn

public boolean dependsOn(Variable x)

Checks whether the expression has any dependence on the variable x.

toString

public java.lang.String toString()

Get a print string representation of this expression. (Of course, every object defines toString(). It is included here to remind you that classes that implement the Expression interface should have a print string representation that looks like a mathematical expression.)

Overrides:

toString in class java.lang.Object