| pdClasses(nlme) | R Documentation |
Standard classes of positive-definite matrices (pdMat)
structures available in the nlme library.
pdSymm |
general positive-definite matrix, with no additional structure |
pdDiag |
diagonal |
pdIdent |
multiple of an identity |
pdCompSymm |
compound symmetry structure (constant diagonal and constant off-diagonal elements) |
pdBlocked |
block-diagonal matrix, with diagonal blocks of any
"atomic" pdMat class |
pdNatural |
general positive-definite matrix in natural parametrization (i.e. parametrized in terms of standard deviations and correlations). The underlying coefficients are not unrestricted, so this class should NOT be used for optimization. |
Users may define their own pdMat classes by specifying a
constructor function and, at a minimum, methods for the
functions pdConstruct, pdMatrix and coef. For
examples of these functions, see the methods for classes pdSymm
and pdDiag.
Jose Pinheiro and Douglas Bates
pdCompSymm, pdDiag,
pdIdent, pdNatural, pdSymm