sar</p>
</div></blockquote>
<p><strong>f1: float, optional</strong></p>
<blockquote>
<div><p>The frequency derivative of the pulsar</p>
</div></blockquote>
<p><strong>f2: float, optional</strong></p>
<blockquote>
<div><p>The second derivative of the frequency</p>
</div></blockquote>
<p><strong>f3: float, optional</strong></p>
<blockquote>
<div><p>The third derivative of the frequency</p>
</div></blockquote>
<p><strong>f4: float, optional</strong></p>
<blockquote>
<div><p>The fourth derivative of the frequen