# Rev Language Reference

## mvCorrelationMatrixSingleElementBeta - Correlation Matrix Beta proposal.

Beta proposal on a random element of a correlation matrix.

### Usage

mvCorrelationMatrixSingleElementBeta(MatrixReal x, RealPos alpha, Bool tune, RealPos weight, Probability tuneTarget)

### Arguments

 x : MatrixReal ( pass by reference) The variable on which this move operates. alpha : RealPos (pass by value) The shape of the beta distribution to draw from. Default : 10 tune : Bool (pass by value) Should we tune the scaling factor during burnin? Default : TRUE weight : RealPos (pass by value) The weight how often on average this move will be used per iteration. Default : 1 tuneTarget : Probability (pass by value) The acceptance probability targeted by auto-tuning. Default : 0.44

### Details

This move chooses a single element of the correlation matrix at random, and draws a proposed value from a Beta distribution centered on the current value (and stretched to range from -1 to 1).

### Example


# we draw a correlation matrix from an LKJ distribution
R ~ dnLKJ(eta=1, dim=5)

# we specify a beta move on the correlation matrix
moves[1] = mvCorrelationMatrixSingleElementBeta(R, alpha=10.0)