Dear all,
I used modFit of the package FME to fit a set of ODE to a ste of
experimental data.
The summary of this fit give me the following error
> summary(Fit)
Residual standard error: 984.1 on 452 degrees of freedom
Error in cov2cor(x$cov.unscaled) : 'V' is not a square numeric matrix
In addition: Warning message:
In summary.modFit(Fit) : Cannot estimate covariance; system is singular
This is due becasue the Hessian matrix has all the entries equal to 0 in my
system.
In these cases, on the help page of modFit, it is suggested to use modMCMC
to generate new sets of parameters. modMCMC performs a Markov Chain Monte
Carlo simulation.
I do not understand very well how modMCMC can be used in a context of
parameter estimation. Could someone help me in understanding the use of this
function and its utility for parameter fitting?
Thank you very much in advance,
Paola.
--
*Paola Lecca, PhD*
*The Microsoft Research - University of Trento*
*Centre for Computational and Systems Biology*
*Piazza Manci 17 38123 Povo/Trento, Italy*
*Phome: +39 0461282843*
*Fax: +39 0461282814*
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