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##### 非中心β分佈(Noncentral Beta Distribution)

`#include <boost/math/distributions/non_central_beta.hpp>`

```namespace boost{ namespace math{

template <class RealType = double,
class Policy   = policies::policy<> >
class non_central_beta_distribution;

typedef non_central_beta_distribution<> non_central_beta;

template <class RealType, class Policy>
class non_central_beta_distribution
{
public:
typedef RealType  value_type;
typedef Policy    policy_type;

// 構造函數:
non_central_beta_distribution(RealType alpha, RealType beta, RealType lambda);

// 形狀參數訪問函數(Accessor to shape parameters):
RealType alpha()const;
RealType beta()const;

// 非中心參數lambda訪問函數(Accessor to non-centrality parameter lambda):
RealType non_centrality()const;
};

}} // namespaces
```

##### 成員函數
```non_central_beta_distribution(RealType a, RealType b, RealType lambda);
```

```RealType alpha()const;
```

```RealType beta()const;
```

```RealType non_centrality()const;
```

##### 精確度

α, β,λ < 200

α,β,λ > 200

53

Win32, Visual C++ 8

64

RedHat Linux IA32, gcc-4.1.1

64

Redhat Linux IA64, gcc-3.4.4

113

HPUX IA64, aCC A.06.06

##### 實現

Denise Benton and K. Krishnamoorthy, "Computing discrete mixtures of continuous distributions: noncentral chisquare, noncentral t and the distribution of the square of the sample multiple correlation coefficient", Computational Statistics & Data Analysis 43 (2003) 249-267.

Russell V. Lenth, "Algorithm AS 226: Computing Noncentral Beta Probabilities", Applied Statistics, Vol. 36, No. 2. (1987), pp. 241-244.

H. Frick, "Algorithm AS R84: A Remark on Algorithm AS 226: Computing Non-Central Beta Probabilities", Applied Statistics, Vol. 39, No. 2. (1990), pp. 311-312.

Ming Long Lam, "Remark AS R95: A Remark on Algorithm AS 226: Computing Non-Central Beta Probabilities", Applied Statistics, Vol. 44, No. 4. (1995), pp. 551-552.

Harry O. Posten, "An Effective Algorithm for the Noncentral Beta Distribution Function", The American Statistician, Vol. 47, No. 2. (May, 1993), pp. 129-131.

R. Chattamvelli, "A Note on the Noncentral Beta Distribution Function", The American Statistician, Vol. 49, No. 2. (May, 1995), pp. 231-234.

PDF函數的計算使用 Benton 和 Krishnamoorthy 發明的方法以及下面的關係式：