### Name: pdMatrix
### Title: Extract Matrix or Square-Root Factor from a pdMat Object
### Aliases: pdMatrix pdMatrix.pdBlocked pdMatrix.pdCompSymm
###   pdMatrix.pdDiag pdMatrix.pdIdent pdMatrix.pdMat pdMatrix.pdSymm
###   pdMatrix.pdNatural
### Keywords: models

### ** Examples

pd1 <- pdSymm(diag(1:4))
pdMatrix(pd1)