[ADMB Users] matrix not positive definite

dave fournier davef at otter-rsch.com
Sun Feb 10 11:00:08 PST 2013

On 13-02-10 10:39 AM, Mollie Brooks wrote:

Its pretty complicated, but the first question would be why should it be 
positive definite.
Without understanding the special structure all I see is a way of 
parameterizing a
symmetric matrix via a bunch of parameters.  since S_ij = S_ji  by
construction it is symmetric, but why positive definite.

> Thanks for the response.
> I'm attaching the code and a tiny simulated data set. I can send a larger simulated dataset if it helps. I also attached the R code I used to simulate the data.
> The attached pdf contains the formula for the variance covariance matrix as "Process Error". The "Predictions" are temporally autocorrelated latent variables that determine the Bernoulli process of whether or not there is water in the pond.
> thanks,
> Mollie
> Mollie Brooks
> Postdoctoral Researcher, Ponciano Lab
> Biology Department, University of Florida
> http://people.biology.ufl.edu/mbrooks
> On 10 Feb 2013, at 11:54 AM, dave fournier wrote:
>> Hard to say much that isn't probably wrong without seeing your code etc.
>> _______________________________________________
>> Users mailing list
>> Users at admb-project.org
>> http://lists.admb-project.org/mailman/listinfo/users

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.admb-project.org/pipermail/users/attachments/20130210/61894513/attachment.html>

More information about the Users mailing list