Package com.singularsys.jep.functions

Class Binomial

java.lang.Object

com.singularsys.jep.functions.PostfixMathCommand

com.singularsys.jep.functions.BinaryFunction

com.singularsys.jep.functions.Binomial

All Implemented Interfaces:

PostfixMathCommandI, Serializable

public class Binomial
extends BinaryFunction

Binomial coefficients: binom(n,i). Requires n,i integers >=0. Often written as nCi or column vector (n,i).

The following rules apply:
(n,0) = 1, (n,1) = n, (n,n-1) = n, (n,n) = 1
(n,i) = n! / ( i! (n-i)! )
Pascals triangle rule: (n,i) = (n-1,i-1) + (n-1,i)
Binomial theorem: (a+b)^n = sum (n,i) a^i b^(n-i), i=0..n.

For efficiency the binomial coefficients are stored in a static array.

Author:

Rich Morris Created on 13-Feb-2005

See Also:

• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class com.singularsys.jep.functions.BinaryFunction

BinaryFunction.BiFunctionWithException<T>

Field Summary

Fields inherited from class com.singularsys.jep.functions.PostfixMathCommand

curNumberOfParameters, description, name, NaN, numberOfParameters

Constructor Summary

Constructors

Constructor	Description
Binomial()

Method Summary

Modifier and Type	Method	Description
static int	binom(int n, int i)	Returns the binomial coefficients. nCi.
Object	eval(Object l, Object r)	Evaluate the function

Methods inherited from class com.singularsys.jep.functions.BinaryFunction

instanceOf, instanceOf, instanceOf, instanceOf, run

Methods inherited from class com.singularsys.jep.functions.PostfixMathCommand

asArray, asBool, asDouble, asInt, asLong, asStrictInt, asString, asType, checkNumberOfParameters, getDescription, getDescription, getDescriptionWithType, getName, getNumberOfParameters, setCurNumberOfParameters, setDescription, setName, toString, toString

Methods inherited from class java.lang.Object

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

Constructor Details

Binomial

public Binomial()

Method Details

eval

public Object eval(Object l,
 Object r)
            throws EvaluationException

Description copied from class: BinaryFunction

Evaluate the function

Specified by:

eval in class BinaryFunction

Parameters:

l - lhs argument

r - rhs argument

Returns:

the results

Throws:

EvaluationException - if the function cannot be evaluated.

binom

public static int binom(int n,
 int i)
                 throws ArrayIndexOutOfBoundsException

Returns the binomial coefficients. nCi.

Parameters:

n - n

i - i

Returns:

the binomial coefficient

Throws:

ArrayIndexOutOfBoundsException - if n<0, i<0 or i>n