By John C. Platt (1999) MIT
Main
-
Modified (enhanced) sigmoid function
$$p_i = \frac{1}{1 + \exp(Ax + b)}$$ -
Scaled cost function
$$J = -\frac{1}{m}\sum_{i}{(t_i\log{p_i} + (1 - t_i)\log(1 - p_i))}$$
where $t_i\in\{0, 1\}$ is the class label.