<span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">nphot</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">tstart</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">tstop</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">f0</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">f1</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span