.TH "std::gamma_distribution< _RealType >" 3cxx "Thu Aug 2 2012" "libstdc++" \" -*- nroff -*-
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.SH NAME
std::gamma_distribution< _RealType > \- 
.SH SYNOPSIS
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.PP
.SS "Public Types"

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.RI "typedef _RealType \fBinput_type\fP"
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.RI "typedef _RealType \fBresult_type\fP"
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.SS "Public Member Functions"

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.RI "_RealType \fBalpha\fP () const "
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.RI "\fBgamma_distribution\fP (const result_type &__alpha_val=result_type(1))"
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.RI "template<class _UniformRandomNumberGenerator > result_type \fBoperator()\fP (_UniformRandomNumberGenerator &__urng)"
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.RI "void \fBreset\fP ()"
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.SS "Friends"

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.RI "template<typename _RealType1 , typename _CharT , typename _Traits > \fBstd::basic_ostream\fP< _CharT, 
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_Traits > & \fBoperator<<\fP (\fBstd::basic_ostream\fP< _CharT, _Traits > &__os, const \fBgamma_distribution\fP< _RealType1 > &__x)"
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.RI "template<typename _CharT , typename _Traits > \fBstd::basic_istream\fP< _CharT, 
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_Traits > & \fBoperator>>\fP (\fBstd::basic_istream\fP< _CharT, _Traits > &__is, \fBgamma_distribution\fP &__x)"
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.SH "Detailed Description"
.PP 

.SS "template<typename _RealType = double>class std::gamma_distribution< _RealType >"
A gamma continuous distribution for random numbers\&. 

The formula for the gamma probability mass function is $ p(x) = \frac{1}{\Gamma(\alpha)} x^{\alpha - 1} e^{-x} $\&. 
.PP
Definition at line 2320 of file tr1_impl/random\&.
.SH "Constructor & Destructor Documentation"
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.SS "template<typename _RealType = double> \fBstd::gamma_distribution\fP< _RealType >::\fBgamma_distribution\fP (const result_type &__alpha_val = \fCresult_type(1)\fP)\fC [inline]\fP, \fC [explicit]\fP"
Constructs a gamma distribution with parameters $ \alpha $\&. 
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Definition at line 2332 of file tr1_impl/random\&.
.SH "Member Function Documentation"
.PP 
.SS "template<typename _RealType = double> _RealType \fBstd::gamma_distribution\fP< _RealType >::alpha () const\fC [inline]\fP"
Gets the $ \alpha $ of the distribution\&. 
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Definition at line 2343 of file tr1_impl/random\&.
.SS "template<typename _RealType > template<class _UniformRandomNumberGenerator > \fBgamma_distribution\fP< _RealType >::result_type \fBstd::gamma_distribution\fP< _RealType >::operator() (_UniformRandomNumberGenerator &__urng)"
Cheng's rejection algorithm GB for alpha >= 1 and a modification of Vaduva's rejection from Weibull algorithm due to Devroye for alpha < 1\&.
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References: Cheng, R\&. C\&. 'The Generation of Gamma Random Variables with Non-integral
Shape Parameter\&.' Applied Statistics, 26, 71-75, 1977\&.
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Vaduva, I\&. 'Computer Generation of Gamma Gandom Variables by Rejection
and Composition Procedures\&.' Math\&. Operationsforschung and Statistik, Series in Statistics, 8, 545-576, 1977\&.
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Devroye, L\&. 'Non-Uniform Random Variates Generation\&.' Springer-Verlag, New York, 1986, Ch\&. IX, Sect\&. 3\&.4 (+ Errata!)\&. 
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Definition at line 1501 of file random\&.tcc\&.
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References std::exp(), std::log(), and std::pow()\&.
.SS "template<typename _RealType = double> void \fBstd::gamma_distribution\fP< _RealType >::reset ()\fC [inline]\fP"
Resets the distribution\&. 
.PP
Definition at line 2350 of file tr1_impl/random\&.
.SH "Friends And Related Function Documentation"
.PP 
.SS "template<typename _RealType = double> template<typename _RealType1 , typename _CharT , typename _Traits > \fBstd::basic_ostream\fP<_CharT, _Traits>& operator<< (\fBstd::basic_ostream\fP< _CharT, _Traits > &__os, const \fBgamma_distribution\fP< _RealType1 > &__x)\fC [friend]\fP"
Inserts a gamma_distribution random number distribution \fC__x\fP into the output stream \fC__os\fP\&.
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\fBParameters:\fP
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\fI__os\fP An output stream\&. 
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\fI__x\fP A gamma_distribution random number distribution\&.
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\fBReturns:\fP
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The output stream with the state of \fC__x\fP inserted or in an error state\&. 
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.SS "template<typename _RealType = double> template<typename _CharT , typename _Traits > \fBstd::basic_istream\fP<_CharT, _Traits>& operator>> (\fBstd::basic_istream\fP< _CharT, _Traits > &__is, \fBgamma_distribution\fP< _RealType > &__x)\fC [friend]\fP"
Extracts a gamma_distribution random number distribution \fC__x\fP from the input stream \fC__is\fP\&.
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\fBParameters:\fP
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\fI__is\fP An input stream\&. 
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\fI__x\fP A gamma_distribution random number generator engine\&.
.RE
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\fBReturns:\fP
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The input stream with \fC__x\fP extracted or in an error state\&. 
.RE
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Definition at line 2382 of file tr1_impl/random\&.

.SH "Author"
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Generated automatically by Doxygen for libstdc++ from the source code\&.