Package org.mariuszgromada.math.mxparser

Class RecursiveArgument

java.lang.Object

org.mariuszgromada.math.mxparser.PrimitiveElement

org.mariuszgromada.math.mxparser.Argument

org.mariuszgromada.math.mxparser.RecursiveArgument

public class RecursiveArgument
extends Argument

RecursiveArgument class enables to declare the argument (variable) which is defined in a recursive way. Such an argument can be used in further processing in expressions, functions and dependent or recursive arguments.
For example:

• 'fib(n) = fin(n-1)+fib(n-2), fib(0) = 0, fib(1) = 1'
• 'factorial(n) = n*factorial(n-1), factorial(0) = 1'

When creating an argument you should avoid:

• names reserved as parser keywords, in general words known in mathematical language as function names, operators (for example: sin, cos, +, -, etc...). Please be informed that after associating the argument with the expression, function or dependent/recursive argument its name will be recognized by the parser as reserved key word. It means that it could not be the same as any other key word known by the parser for this particular expression.
• defining statements with increasing index: 'a(n) = a(n+1) + ... ', otherwise you will get Double.NaN
• if recursion is not properly defined you will get Double.NaN in the result. This is due to the recursion counter inside of the recursive argument. Calculating n-th element requires no more than n recursion steps (usually less than n).
• For negative 'n' you will get Double.NaN.

Version:

3.0.0

See Also:

• Argument
• Expression
• Function
• Constant

Field Summary

Fields

Modifier and Type	Field	Description
static final String	TYPE_DESC_RECURSIVE
static final int	TYPE_ID_RECURSIVE	Type identifier for recursive arguments.

Fields inherited from class org.mariuszgromada.math.mxparser.Argument

ARGUMENT_INITIAL_VALUE, BODY_EXTENDED, BODY_RUNTIME, DEPENDENT_ARGUMENT, FREE_ARGUMENT, n, NO_SYNTAX_ERRORS, NOT_FOUND, RECURSIVE_ARGUMENT, SYNTAX_ERROR_OR_STATUS_UNKNOWN, TYPE_DESC, TYPE_ID

Constructor Summary

Constructors

Constructor	Description
RecursiveArgument(String argumentName, String recursiveExpressionString, String indexName)	Constructor - creates recursive argument.
RecursiveArgument(String argumentName, String recursiveExpressionString, Argument n, PrimitiveElement... elements)	Constructor - creates recursive argument.
RecursiveArgument(String argumentDefinitionString, PrimitiveElement... elements)	Constructor - creates argument based on the argument definition string.

Method Summary

Modifier and Type	Method	Description
void	addBaseCase(int index, double value)	Adds base case
double	getArgumentValue(double index)	Gets recursive argument value
void	resetAllCases()	Clears all based cases and stored calculated values

Methods inherited from class org.mariuszgromada.math.mxparser.Argument

addArguments, addConstants, addConstants, addDefinitions, addFunctions, checkSyntax, clone, defineArgument, defineArguments, defineConstant, defineFunction, getArgument, getArgument, getArgumentBodyType, getArgumentExpressionString, getArgumentIndex, getArgumentName, getArgumentsNumber, getArgumentType, getArgumentValue, getComputingTime, getConstant, getConstant, getConstantIndex, getConstantsNumber, getDescription, getErrorMessage, getFunction, getFunction, getFunctionIndex, getFunctionsNumber, getRecursiveMode, getVerboseMode, removeAllArguments, removeAllConstants, removeAllFunctions, removeArguments, removeArguments, removeConstants, removeConstants, removeDefinitions, removeFunctions, removeFunctions, setArgumentExpressionString, setArgumentName, setArgumentValue, setDescription, setSilentMode, setVerboseMode

Methods inherited from class org.mariuszgromada.math.mxparser.PrimitiveElement

getMyTypeId

Methods inherited from class java.lang.Object

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

Field Details

TYPE_ID_RECURSIVE

public static final int TYPE_ID_RECURSIVE

Type identifier for recursive arguments.

See Also:

• Constant Field Values

TYPE_DESC_RECURSIVE

public static final String TYPE_DESC_RECURSIVE

See Also:

• Constant Field Values

Constructor Details

RecursiveArgument

public RecursiveArgument(String argumentName,
 String recursiveExpressionString,
 String indexName)

Constructor - creates recursive argument.

Parameters:

argumentName - the argument name

recursiveExpressionString - the recursive expression string

indexName - index argument name

RecursiveArgument

public RecursiveArgument(String argumentName,
 String recursiveExpressionString,
 Argument n,
 PrimitiveElement... elements)

Constructor - creates recursive argument.

Parameters:

argumentName - the argument name

recursiveExpressionString - the recursive expression string

n - the index argument

elements - Optional elements list (variadic - comma separated) of types: Argument, Constant, Function

See Also:

• PrimitiveElement
• Argument

RecursiveArgument

public RecursiveArgument(String argumentDefinitionString,
 PrimitiveElement... elements)

Constructor - creates argument based on the argument definition string.

Parameters:

argumentDefinitionString - Argument definition string, i.e.:

• 'x' - only argument name
• 'x=5' - argument name and argument value
• 'x=2*5' - argument name and argument value given as simple expression
• 'x=2*y' - argument name and argument expression (dependent argument 'x' on argument 'y')
• 'x(n)=x(n-1)+x(n-2)' - for recursive arguments)

elements - Optional elements list (variadic - comma separated) of types: Argument, Constant, Function

See Also:

• PrimitiveElement
• Argument

Method Details

addBaseCase

public void addBaseCase(int index,
 double value)

Adds base case

Parameters:

index - the base case index

value - the base case value

resetAllCases

public void resetAllCases()

Clears all based cases and stored calculated values

getArgumentValue

public double getArgumentValue(double index)

Gets recursive argument value

Parameters:

index - the index

Returns:

value as double