I think the problem is with the (2,2) element in your hessian, unless
that is a typo.
Cheers
David Cross
d.cr...@tcu.edu
www.davidcross.us
On Nov 16, 2010, at 8:33 PM, Jimmy Martina wrote:
Hi, R-folks:
I have been tryin many combination of parameter to make Matern
variogram to work, but I can't find the available one. I'm near to
be crazy.
I tiped:
Año2003Selg.lf<-
likfit
(Año2003Selg
,cov
.model
=
"matern
",ini
.cov
.pars
=
c
(1.5,14
),kappa
=
2.5
,fix
.kappa=FALSE,nugget=0.08,lambda=0.008,fix.lambda=FALSE,hessian=TRUE)
the hessian shows:
$hessian
[,1] [,2] [,3] [,4]
[1,] 9.139986 -8.562736e+00 41.648355 -3.801615
[2,] -8.562736 3.351952e+159 -147.279881 -7.083089
[3,] 41.648355 -1.472799e+02 347.493191 -7.509035
[4,] -3.801615 -7.083089e+00 -7.509035 90.681917
Then, I put: solve(Año2003Selg.lf$info.minimisation.function$hessian)
...and it's shown as following:
Error in solve.default(Año2003Selg.lf$info.minimisation.function
$hessian) :
sistem is computationally singular: number of reciprocity
condition= 1.05091e-159
on account of I work in Spanish, it's shown:
Error in solve.default(Año2003Selg.lf$info.minimisation.function
$hessian) :
sistema es computacionalmente singular: número de condición
recíproco = 1.05091e-159
I also wander if there is any limit for kappa. Which one would be
the maximun. As far as I'm concerned, it must be always major than
cero, right?. I also know that its values depend on the tendency of
cloud semivariogram, if it flattens slowly (Gaussian) it's major.
I'll thank the one available to answer my desperate question.
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