pan> <span class="n">y</span><span class="p">)</span>  <span class="c1"># radius at y</span>

        <span class="n">theta</span> <span class="o">=</span> <span class="n">phi</span> <span class="o">*</span> <span class="n">i</span>  <span class="c1"># golden angle increment</span>

        <span class="n">x</span> <span class="o">=</span> <span class="n">math</span><span class="o">.</span><span class="n">cos</span><span class="p">(</span><span class="n">theta</span><span class="p">)</span> <span class="o">