expcov {spatial} | R Documentation

## Spatial Covariance Functions

### Description

Spatial covariance functions for use with `surf.gls`.

### Usage

    expcov(r, d, alpha=0, se=1)
    gaucov(r, d, alpha=0, se=1)
    sphercov(r, d, alpha=0, se=1, D=2)

### Arguments

`r` | vector of distances at which to evaluate the covariance
`d` | range parameter
`alpha` | proportion of nugget effect
`se` | standard deviation at distance zero
`D` | dimension of spheres.

### Value

vector of covariance values.

### See Also

`surf.gls`

### Examples

    data(topo)
    topo.kr <- surf.ls(2, topo)
    correlogram(topo.kr, 25)
    d <- seq(0, 7, 0.1)
    lines(d, expcov(d, 0.7))