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<table width="100%" summary="page for expcov {spatial}"><tr><td>expcov {spatial}</td><td align="right">R Documentation</td></tr></table>
<h2>Spatial Covariance Functions</h2>


<h3>Description</h3>

<p>
Spatial covariance functions for use with <code>surf.gls</code>.
</p>


<h3>Usage</h3>

<pre>
expcov(r, d, alpha = 0, se = 1)
gaucov(r, d, alpha = 0, se = 1)
sphercov(r, d, alpha = 0, se = 1, D = 2)
</pre>


<h3>Arguments</h3>

<table summary="R argblock">
<tr valign="top"><td><code>r</code></td>
<td>
vector of distances at which to evaluate the covariance
</td></tr>
<tr valign="top"><td><code>d</code></td>
<td>
range parameter
</td></tr>
<tr valign="top"><td><code>alpha</code></td>
<td>
proportion of nugget effect
</td></tr>
<tr valign="top"><td><code>se</code></td>
<td>
standard deviation at distance zero
</td></tr>
<tr valign="top"><td><code>D</code></td>
<td>
dimension of spheres.
</td></tr>
</table>

<h3>Value</h3>

<p>
vector of covariance values.</p>

<h3>References</h3>

<p>
Ripley, B. D. (1981) <EM>Spatial Statistics.</EM> Wiley.
</p>
<p>
Venables, W. N. and Ripley, B. D. (2002)
<EM>Modern Applied Statistics with S.</EM> Fourth edition.  Springer.
</p>


<h3>See Also</h3>

<p>
<code><a href="surf.gls.html">surf.gls</a></code>
</p>


<h3>Examples</h3>

<pre>
data(topo, package="MASS")
topo.kr &lt;- surf.ls(2, topo)
correlogram(topo.kr, 25)
d &lt;- seq(0, 7, 0.1)
lines(d, expcov(d, 0.7))
</pre>



<hr><div align="center">[Package <em>spatial</em> version 7.2-44 <a href="00Index.html">Index]</a></div>

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