# BEAST v2.6.7 Documentation: beast.math.distributions.Gamma

BEASTObject that performs calculations based on the State.

A class that describes a parametric distribution, that is, a distribution that takes some parameters/valuables as inputs and can produce (cumulative) densities and inverse cumulative densities.

Gamma distribution. for x>0 g(x;alpha,beta) = 1/Gamma(alpha) beta^alpha} x^{alpha - 1} e^{-rac{x}{beta}}If the input x is a multidimensional parameter, each of the dimensions is considered as a separate independent component.

## Inputs:

alpha, beta, mode, offset

beta
type: beast.core.parameter.RealParameter |

second parameter depends on mode, defaults to 2.For mode=ShapeScale beta is interpreted as scale. For mode=ShapeRate beta is interpreted as rate. For mode=ShapeMean beta is interpreted as mean.For mode=OneParameter beta is ignored. |

Optional input |

mode
type: beast.math.distributions.Gamma$mode |

determines parameterisation. For ShapeScale beta is interpreted as scale. For ShapeRate beta is interpreted as rate. For ShapeMean beta is interpreted as mean.For OneParameter beta is ignored. |

Optional input |

offset
type: java.lang.Double |

offset of origin (defaults to 0) |

Optional input. Default: 0.0 |