Fits a Trend Surface by Least-squares

DESCRIPTION:

Fits a trend surface by least-squares.

USAGE:

surf.ls(np, x, y, z)
residuals.trls(object, ...)
fitted.trls(object, ...)
deviance.trls(object, ...)
df.residual.trls(object, ...)
extractAIC.trls(fit, scale, k = 2, ...)

REQUIRED ARGUMENTS:

np
degree of polynomial surface
x
x coordinates or a data frame with columns x, y, z
y
y coordinates
z
z coordinates. Will supersede x$z
object, fit
a fit inheriting from class "trls"

OPTIONAL ARGUMENTS:

scale
unused for this method
k
the multiple of the number of degrees of freedom to be used.
...
arguments passed to or from other methods.

VALUE:

list with components
beta
the coefficients
x
y
z


and others for internal use only.

SEE ALSO:

,

EXAMPLES:

library(MASS)
topo.kr <- surf.ls(2, topo)
trsurf <- trmat(topo.kr, 0, 6.5, 0, 6.5, 50)
eqscplot(trsurf, type = "n")
contour(trsurf, add = T)
points(topo)

eqscplot(trsurf, type = "n")
contour(trsurf, add = T)
plot(topo.kr, add = T)
title(xlab = "Circle radius proportional to Cook's influence statistic")