>, back$angle +<span class="st"> </span><span class="dv">3</span>*pi/<span class="dv">2</span>) *<span class="st"> </span><span class="dv">180</span> /<span class="st"> </span>pi

## look at field in first and last media, respectively
last &lt;-<span class="st"> </span><span class="kw">length</span>(M.back$Mr.par)
intensity.par =<span class="st"> </span><span class="kw">c</span>(M.front$Ml.par[[<span class="dv">1</span>]] , M.back$Mr.par[[last]])
intensity.perp =<span class="st"> </span><span class="kw">c</