XploRe Help : SPKRsphercov

Keywords - Function groups - @ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Library:	spatial
See also:	SPKRsurfls SPKRsurfgls SPKRexpcov SPKRgaucov SPKRtrmat SPKRprmat SPKRsemat SPKRcorrelogram SPKRvariogram SPKRmultcontours

Quantlet:		SPKRsphercov
Description:		spatial covariance function for use with SPKRsurfgls

Reference(s):

Venables, W. N., Ripley, B. D. (1999): Modern Applied Statistics with S-Plus, Third Edition, Springer, New York

Link:

Tutorial: Spatial statistics

Usage:	`res = SPKRsphercov(r, d, alpha, se {, D})`
Input:
	`r`	n x 1 vector, distances used to evaluate the covariance
	`d`	scalar, range parameter
	`alpha`	scalar, proportion of nugget effect
	`se`	scalar, standard deviation at distance zero
	`D`	optional scalar, dimension of spheres; default D = 2
Output:
	`res`	n x 1 vector, covariance values

Note:

Code from Venables, Ripley (1999) forms the basis of this quantlet. Also check this reference for more details.

Example:

; loads the spatial statistics library library("spatial") ; calculates spatial covariance function SPKRsphercov ; with d = 0.7, alpha = 0, se = 1, and D = 2 on a grid ; from 0 through 7 ddat = grid(0, 0.1, 71) linedat = ddat ~ SPKRsphercov(ddat, 0.7, 0, 1, 2) ; creates a display and draws the covariance disp = createdisplay(1, 1) show(disp, 1, 1, linedat)

Result:

A plot of the vector of covariance values. Typically, this quantlet
is used together with SPKRsurfgls or SPKRcorrelogram.

Author: J. Symanzik, 20000725 license MD*Tech