n class="dt">angle =</span> <span class="kw">seq</span>(<span class="dv">0</span>, pi, <span class="dt">length=</span><span class="dv">100</span>), 
             <span class="dt">epsilon =</span> <span class="kw">list</span>(<span class="fl">1.0</span>^<span class="dv">2</span>, <span class="fl">1.0</span>^<span class="dv">2</span>),
             <span class="dt">thickness =</span> <span class="kw">c</span>(<span class="dv">0</span>, <span class="dv">0</span>),
             <span class="dt">d =</span> <span