spherical.gc {gcKrig} | R Documentation |
corr.gc
The spherical correlation function in spatial statistics.
By default, range parameter is not available, so
this function is used for likelihood inference and spatial prediction in function mlegc
and predgc
.
Users need to specify if the correlation model includes a nugget effect
nugget = TRUE
or not nugget = FALSE
.
When both range and nugget parameters are given,
the function is used for simulation with function simgc
in package gcKrig
.
spherical.gc(range = NULL, nugget = TRUE)
range |
a non-negative scalar of the range parameter in the spherical correlation function. |
nugget |
the nugget effect of the correlation function. If specified, it must be a scalar between 0 and 1. |
The spherical correlation function with a nugget \tau^2
is of the form:
\rho(h) = (1-\tau^2) (1 - 1.5(h/\phi) + 0.5(-h/\phi)^3)
when h > 0
and \rho(h) = 1
when h = 0
, h
is distance.
An object of class corr.gc
representing the correlation component.
Zifei Han hanzifei1@gmail.com