gridripper::math::expr::Expr Class Reference

Evaluates mathematical expressions or functions. More...

Inheritance diagram for gridripper::math::expr::Expr:

List of all members.

Public Member Functions
	Expr (String s) throws Error
	Construct a mathematical expression containing numbers only.
	Expr (String s, List< StkOp > f, StkOpRepository funcRep) throws Error
	Construct a function from the specified string and variables.
String	getString ()
	Gets the expression as a string.
String	getProgramListString ()
	Gets the "program" as a printable string.
double	eval ()
	Evaluate the expression.
boolean	isConstant ()
	Returns true if the expression is determined to be a constant.
boolean	dependsOn (StkOp f)
	Returns true if the expression contains the specified function.
boolean	dependsOnVariables ()
	Returns true if the expression uses external variables.
void	replaceVar (String name, StkVar var)
	Replaces all occurances of a variable with another one in the program.
void	evalStack (StkPointer sp0)
	Evaluates the stack.
StkOp[]	getInternalProgram ()
	Gets the "program".
String	getClassName ()
	Gets the class name.
Static Public Member Functions
static int	findExprEnd (String str, int i)
	Finds end of subexpression starting at the specified character.
Classes
class	Error
	Exception thrown by the Expr constructor in case of syntax error.

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Detailed Description

Evaluates mathematical expressions or functions.

Example:

f(x) = x^0.5*atan(1)/sqrt(pi)

<blockquote>

    StkOp vX = new StkVar("x");           // define variable
    List<StkOp> funcs = new ArrayList<StkOp>();
    funcs.add(vX);
    funcs.add(new StkConst("pi", Math.PI)); // define a constant
    try {
        Expr expr = new Expr("x^0.5*atan(1)/sqrt(pi)", funcs); // create Expr
        vX.value = 5; // set value of variable
        System.out.println("f(5) = " + expr.eval());  // calculate f(5)
    } catch(Expr.Error ex) {
        ex.printStackTrace();
    }
 

</blockquote>

Version:

GridRipper 0.5, 06/13/2009

Since:

GROMIT 0.2 (2001)

Author:

Peter Csizmadia

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Constructor & Destructor Documentation

gridripper::math::expr::Expr::Expr

(

String

s

)

throws Error [inline]

Construct a mathematical expression containing numbers only.

Parameters:

s

the expression

gridripper::math::expr::Expr::Expr	(	String	s,
		List< StkOp >	f,
		StkOpRepository	funcRep
	)			throws Error [inline]

Construct a function from the specified string and variables.

Parameters:

	s	the expression
	f	extra functions and variables
	funcRep	function repository

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Member Function Documentation

String gridripper::math::expr::Expr::getString

(

)

[inline]

Gets the expression as a string.

Returns:

the expression

String gridripper::math::expr::Expr::getProgramListString

(

)

[inline]

Gets the "program" as a printable string.

Useful for debugging.

Returns:

the program list

double gridripper::math::expr::Expr::eval

(

)

[inline]

Evaluate the expression.

boolean gridripper::math::expr::Expr::dependsOn

(

StkOp

f

)

[inline, virtual]

Returns true if the expression contains the specified function.

Subexpressions are also checked, recursively.

Reimplemented from gridripper::math::expr::StkFunc.

boolean gridripper::math::expr::Expr::dependsOnVariables

(

)

[inline]

Returns true if the expression uses external variables.

void gridripper::math::expr::Expr::replaceVar	(	String	name,
		StkVar	var
	)			[inline]

Replaces all occurances of a variable with another one in the program.

Parameters:

	name	the variable name
	var	the new variable

void gridripper::math::expr::Expr::evalStack

(

StkPointer

sp0

)

[inline, virtual]

Evaluates the stack.

Parameters:

p

the stack pointer

Implements gridripper::math::expr::StkFunc.

StkOp [] gridripper::math::expr::Expr::getInternalProgram

(

)

[inline]

Gets the "program".

Returns:

the array of stack operations

String gridripper::math::expr::Expr::getClassName

(

)

[inline, virtual]

Gets the class name.

Returns:

the class name

Reimplemented from gridripper::math::expr::StkFunc.

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The documentation for this class was generated from the following file:

• gridripper/math/expr/Expr.java