AdvancedOCR.Step.CalculateActivationDerivative C# (CSharp) Method

        public virtual double CalculateActivationDerivative(double weightedInputs)
        {
            double coshx = Math.Cosh(X_STRETCH * weightedInputs);
            double denominator = Math.Cosh(2.0 * X_STRETCH * weightedInputs) + 1;
            double result = DERIVATIVE_STRETCH * coshx * coshx / (denominator * denominator);
            if (double.IsNaN(result))
                throw new Exception("NaN!");
            return result;
        }

 protected void FinaliseErrorSecondDerivatives(Step downstream)
 {
     for (int i = 0; i < downstream.ErrorDerivative.Length; i++)
     {
         double weightedInputs = downstream.WeightedInputs[i];
         double activationDerivative = downstream.CalculateActivationDerivative(weightedInputs);
         downstream.ErrorDerivative[i] *= activationDerivative * activationDerivative;
     }
 }