     
            <span class="c1"># calculate a,b from M and h:</span>
            <span class="n">a</span> <span class="o">=</span> <span class="p">(</span><span class="n">M</span><span class="o">/</span><span class="n">cM</span><span class="p">)</span><span class="o">*</span><span class="n">np</span><span class="o">.</span><span class="n">cos</span><span class="p">(</span><span class="n">h</span><span class="p">)</span>
            <span class="n">b</span> <span class="o">=</span> <span class="p">(</span