/// <summary>
 /// Returns the sigmoid (logit) of the original vector.
 /// </summary>
 /// <param name="value">Original vector</param>
 /// <returns>Sigmoid vector</returns>
 private InsightVector Sigmoid(InsightVector values)
 {
     return new InsightVector(values.Select(x => 1 / (1 + Math.Exp(-x))).ToList());
 }