Matrix gamma distribution

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Matrix gamma
Notation {{\rm {MG}}}_{{p}}(\alpha ,\beta ,{\boldsymbol  \Sigma })
Parameters shape parameter (real)

\beta >0 scale parameter
{\boldsymbol  \Sigma } scale (positive-definite real p\times p matrix)

Support {\mathbf  {X}} positive-definite real p\times p matrix
pdf {\frac  {|{\boldsymbol  \Sigma }|^{{-\alpha }}}{\beta ^{{p\alpha }}\Gamma _{p}(\alpha )}}|{\mathbf  {X}}|^{{\alpha -(p+1)/2}}\exp \left({{\rm {tr}}}\left(-{\frac  {1}{\beta }}{\boldsymbol  \Sigma }^{{-1}}{\mathbf  {X}}\right)\right)

In statistics, a matrix gamma distribution is a generalization of the gamma distribution to positive-definite matrices.[1] It is a more general version of the Wishart distribution, and is used similarly, e.g. as the conjugate prior of the precision matrix of a multivariate normal distribution and matrix normal distribution. The compound distribution resulting from compounding a matrix normal with a matrix gamma prior over the precision matrix is a generalized matrix t-distribution.[citation needed]

This reduces to the Wishart distribution with \beta =2,\alpha ={\frac  {n}{2}}.

See also

Notes

  1. Iranmanesha, Anis, M. Arashib and S. M. M. Tabatabaeya (2010). "On Conditional Applications of Matrix Variate Normal Distribution". Iranian Journal of Mathematical Sciences and Informatics, 5:2, pp. 33–43.

References

  • Gupta, A. K.; Nagar, D. K. (1999) Matrix Variate Distributions, Chapman and Hall/CRC ISBN 978-1584880462
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