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 SPKRexpcov SPKRgaucov SPKRsphercov SPKRtrmat SPKRprmat SPKRsemat SPKRcorrelogram SPKRvariogram SPKRmultcontours

Quantlet: SPKRsurfgls
Description: Fits a trend surface by generalized least squares.

Reference(s):

Link:
Usage: myres = SPKRsurfgls (np, covmod, xmat, nx, dval, alpha, se {, D})
Input:
np scalar - degree of the polynomial surface, an integer in the range 0..6
covmod integer - type of spatial covariance function: 0 = expcov, 1 = gaucov, 2 = sphercov
xmat n x 3 - matrix of locations (x_i, y_i) [columns 1 & 2] and observations z_i [column 3]
nx integer - number of bins used for table of the covariance; increasing nx adds accuracy, but also increases the size of the object
dval scalar - range parameter (for spatial covariance function)
alpha sclar - proportion of nugget effect (for spatial covariance function)
se scalar - standard deviation at distance zero (for spatial covariance function)
D scalar - optional; default D = 2; dimension of spheres (only used for spatial covariance function SPKRsphercov)
Output:
res list - consisting of components x, y, z, np, f, alph, l, r, beta, wz, yy, W, l1f, minx, maxx, covmod, type --
x n x 1 - same as xmat[,1]
y n x 1 - same as xmat[,2]
z n x 1 - same as xmat[,3]
np scalar - same as input value np
f matrix - internal use only
alph matrix - internal use only
l matrix - internal use only
r matrix - internal use only
beta matrix - (np + 1)(np + 2) / 2 coefficients
wz matrix - internal use only
yy matrix - internal use only
W matrix - internal use only
l1f matrix - internal use only
minx 1 x 3 - minimum of columns of xmat
maxx 1 x 3 - maximum of columns of xmat
covmod scalar - same as input value covmod
type string - "trgls"

Note:

Example:

; load the spatial statistics library

library ("spatial")

; read a spatial data set

topo = read("topo.dat")

; calculate a trend surface of order 2, using expcov as

; spatial covariance function with dval = 0.7, alph = 0,

; and se = 1

myres = SPKRsurfgls(2, 0, topo, 1000, 0.7, 0, 1)

Result:

A list consisting of input parameters, intermediate

results, and final results of a trend surface by generalized 

least squares. This list will be used in other spatial

statistics quantlets such as SPKRtrmat, SPKRcorrelogram,

or SPKRvariogram.


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

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

Author: Juergen Symanzik, 000725
(C) MD*TECH Method and Data Technologies, 21.9.2000