Class LogBinomialCoefficient
- java.lang.Object
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- org.apache.commons.numbers.combinatorics.LogBinomialCoefficient
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public final class LogBinomialCoefficient extends java.lang.Object
Natural logarithm of the binomial coefficient. It is "n choose k
", the number ofk
-element subsets that can be selected from ann
-element set.
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Field Summary
Fields Modifier and Type Field Description private static int
LIMIT_M_DOUBLE
The maximum m that can be computed without overflow of a double for any n.private static int
LIMIT_N_DOUBLE
The maximum n that can be computed without overflow of a double for an m.private static int
LIMIT_N_LONG
The maximum n that can be computed without overflow of a long for any m.
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Constructor Summary
Constructors Modifier Constructor Description private
LogBinomialCoefficient()
Private constructor.
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static double
value(int n, int k)
Computes the logarithm of the binomial coefficient.
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Field Detail
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LIMIT_N_LONG
private static final int LIMIT_N_LONG
The maximum n that can be computed without overflow of a long for any m.C(66, 33) < 2^63
.- See Also:
- Constant Field Values
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LIMIT_N_DOUBLE
private static final int LIMIT_N_DOUBLE
The maximum n that can be computed without overflow of a double for an m. C(1029, 514) ~ 1.43e308.- See Also:
- Constant Field Values
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LIMIT_M_DOUBLE
private static final int LIMIT_M_DOUBLE
The maximum m that can be computed without overflow of a double for any n. C(2147483647, 37) ~ 1.39e302.- See Also:
- Constant Field Values
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Method Detail
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value
public static double value(int n, int k)
Computes the logarithm of the binomial coefficient.This returns a finite result for any valid
n choose k
.- Parameters:
n
- Size of the set.k
- Size of the subsets to be counted.- Returns:
log(n choose k)
.- Throws:
java.lang.IllegalArgumentException
- ifn < 0
,k < 0
ork > n
.
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