">\(\binom{x}{y}\)</span> and pronounced “x choose y.”
This function generalizes to real numbers using the gamma function.
For <span class="math inline">\(0 \leq y \leq x\)</span>, <span class="math display">\[ \mathrm{binomial\_coefficient\_log}(x,y) =
\log\Gamma(x+1) - \log\Gamma(y+1) - \log\Gamma(x-y+1). \]</span></p>
<!-- real; log_falling_factorial; (real x, real n); -->
<p></p>
<p><code>real</code> <strong><code>log_falling_factorial</code></strong><code>(real x, real n)</code><br>
Return the log 