Dear all,

I am using the nlme package and trying to modelate the variance- 
covariance matrix of random effects.
However, I do not understand why do I get this error message:


 > M4CompSym <- update(M4,random=A~pdCompSymm(~CED))
Error in pdMatrix.pdCompSymm(x) :
   Cannot extract the matrix from an uninitialized pdMat object

Can anyone please help me?

How do I update one Model using one of the pre-defined matrixes?


Regards,
Sara Mouro



Sara Maltez Mouro

Centro de Ecologia Funcional
Departamento de Botânica
Universidade de Coimbra

sara@gmesintra.com
www.uc.pt/ecology/saramaltezmouro


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