org.matheclipse.core.reflection.system

Class HarmonicNumber

java.lang.Object

org.matheclipse.core.eval.interfaces.AbstractEvaluator

org.matheclipse.core.reflection.system.HarmonicNumber

All Implemented Interfaces:

IFunctionEvaluator, IEvaluator

public class HarmonicNumber
extends AbstractEvaluator

Harmonic number of a given integer value See: Harmonic number

Constructor Summary

Constructors

Constructor and Description
HarmonicNumber()

Method Summary

Modifier and Type	Method and Description
IExpr	evaluate(IAST ast, EvalEngine engine) Symbolic evaluation of a function.
org.apache.commons.math4.fraction.BigFraction	harmonicNumber(int n) The Harmonic number at the index specified
void	setUp(ISymbol symbol) Evaluate built-in rules and define Attributes for a function.

Methods inherited from class org.matheclipse.core.eval.interfaces.AbstractEvaluator

numericEval

Methods inherited from class java.lang.Object

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

Constructor Detail

HarmonicNumber

public HarmonicNumber()

Method Detail

evaluate

public IExpr evaluate(IAST ast,
                      EvalEngine engine)

Description copied from class: AbstractEvaluator

Symbolic evaluation of a function. ast.get(0) (or alternatively ast.head()) contains the head (i.e. the function symbol) of this abstract syntax tree (AST).
From ast.arg1() to ast.get(n) the ast contains the first to n-th argument of the function (alternatively you get the first to fifth argument with the methods arg1(), arg2(),... arg5()).
If necessary use the methods from the Validate class to check the number or types of arguments in the evaluate method.
Note: if the symbolic evaluation isn't possible or no result is found the evaluate method returns with a null value without throwing an exception!

Specified by:

evaluate in interface IFunctionEvaluator

Specified by:

evaluate in class AbstractEvaluator

Parameters:

ast - the abstract syntax tree (AST) which should be evaluated

engine - the users current evaluation engine

Returns:

the evaluated object or null, if evaluation isn't possible

See Also:

Validate, IExpr.head(), IAST.arg1(), IAST.arg2(), IAST.arg3()

harmonicNumber

public org.apache.commons.math4.fraction.BigFraction harmonicNumber(int n)

The Harmonic number at the index specified

Parameters:

n - the index, non-negative.

Returns:

the H_1=1 for n=1, H_2=3/2 for n=2 etc. For values of n less than 1, zero is returned.

setUp

public void setUp(ISymbol symbol)
           throws SyntaxError

Description copied from class: AbstractEvaluator

Evaluate built-in rules and define Attributes for a function.

Specified by:

setUp in interface IEvaluator

Overrides:

setUp in class AbstractEvaluator

Parameters:

symbol - the symbol which should be set up

Throws:

SyntaxError