ject holds hydrographic information (pressure, salinity,
temperature, longitude and latitude) then another set of possibilities
arises.  If <code>i</code> is <code>"sigmaTheta"</code>, then the value of <code><a href="swSigmaTheta.html">swSigmaTheta()</a></code> is
called with <code>x</code> as the sole argument, and the results are returned.
Similarly, <code><a href="swSigma0.html">swSigma0()</a></code> is used if <code>i="sigma0"</code>, and <code><a href="swSpice.html">swSpice()</a></code> is used if
<co