Displaying 1 result from an estimated 1 matches for "scal1and".
2010 Jan 13
1
Problem fitting a non-linear regression model with nls
...in nlsModel(formula, mf, start, wts) : \n singular gradient
matrix at initial parameter estimates\n"
So it seems that I reach a local extremum each time. I know that most
of the problem comes from the choice of the initial values of the
parameters Asym_inf, Asym_inf, n1, n2, tmid1, tmid2, scal1and scal2.
My question is how could I estimate those initial values so that the nls
fitting works.
Thanks in advance
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Nathalie YAUSCHEW-RAGUENES
Ph.D Student
Unit? de Recherches Ecologie Fonctionnelle et Physique de l'Environnement (EPHYSE)
INRA, Centre de Bordeaux - Aquitaine
71 Av Edouard...