 * (r &lt;= 1)\)</p></li>
<li><p>cosine: \(cos(r)\)</p></li>
<li><p>wave: \(sin(r) * (h &gt; 0) / r + (h = 0)\)</p></li>
<li><p>jbessel: \(Bj(h * range)\), Bj is Bessel-J function</p></li>
<li><p>gravity: \((1 + r^2)^{-0.5}\)</p></li>
<li><p>rquad: \((1 + r^2)^{-1}\)</p></li>
<li><p>magnetic: \((1 + r^2)^{-1.5}\)</p></li>
<li><p>none: \(I\)</p></li>
</ul><p><code>nugget_type</code> Details: Let \(I\) be an identity matrix and \(0\)
be the zero matrix. Then parametric
forms for elements the nugget variance a