 (improperly) as a synonym of mutual 
information. It is defined as:
$$IG(X; Y) = \sum_{y \in Y} \sum_{x \in X} p(x, y) \log \left(\frac{p(x, y)}{p(x) p(y)}  \right)$$</p>
<p>In biogram package information gain is computed using following relationship: 
\(IG = E(S) - E(S|F)\)</p>
    <h2 class="hasAnchor" id="note"><a class="anchor" href="#note"></a>Note</h2>

    <p>During calculations \(0 \log 0  = 0\). For a justification see References.</p>
<p>The function was designed to be afast subroutine of 
<code><