s="n">spec</span><span class="p">(</span><span class="n">nfreqs</span><span class="p">,</span><span class="n">ndirs</span><span class="p">))</span>
  <span class="k">do </span><span class="n">concurrent</span><span class="p">(</span><span class="n">nfreq</span> <span class="o">=</span> <span class="mi">1</span><span class="p">:</span><span class="n">nfreqs</span><span class="p">)</span>
    <span class="n">spec</span><span class="p">(</span><span class="n">nfreq</span><span class="p">,:)</span> <span class=