VGAM (version 0.8-1)

Max: Maxima

Description

Generic function for the maxima (maximums) of a model.

Usage

Max(object, ...)

Arguments

object

An object for which the computation or extraction of a maximum (or maxima) is meaningful.

...

Other arguments fed into the specific methods function of the model. Sometimes they are fed into the methods function for Coef.

Value

• The value returned depends specifically on the methods function invoked.

Details

Different models can define a maximum in different ways. Many models have no such notion or definition.

Maxima occur in quadratic and additive ordination, e.g., CQO or UQO or CAO. For these models the maximum is the fitted value at the optimum. For quadratic ordination models there is a formula for the optimum but for additive ordination models the optimum must be searched for numerically. If it occurs on the boundary, then the optimum is undefined. For a valid optimum, the fitted value at the optimum is the maximum.

References

Yee, T. W. (2004) A new technique for maximum-likelihood canonical Gaussian ordination. Ecological Monographs, 74, 685--701.

Yee, T. W. (2006) Constrained additive ordination. Ecology, 87, 203--213.

See Also

Max.qrrvglm, Tol, Opt.

Examples

set.seed(111)  # This leads to the global solution
hspider[,1:6] = scale(hspider[,1:6]) # Standardized environmental vars
p1 = cqo(cbind(Alopacce, Alopcune, Alopfabr, Arctlute, Arctperi,
               Auloalbi, Pardlugu, Pardmont, Pardnigr, Pardpull,
               Trocterr, Zoraspin) ~
         WaterCon + BareSand + FallTwig + CoveMoss + CoveHerb + ReflLux,
         Bestof = 2,
         fam = quasipoissonff, data = hspider, Crow1positive=FALSE)

Max(p1)

index = 1:ncol(p1@y)
persp(p1, col=index, las=1, lwd=2)
abline(h=Max(p1), lty=2, col=index)