code: public void setInitialLearningRate(double initialLearningRate)
      {
          if(Double.isInfinite(initialLearningRate) || Double.isNaN(initialLearningRate) || initialLearningRate <= 0)
              throw new ArithmeticException("Learning rate must be a positive constant, not " + initialLearningRate);
          this.initialLearningRate = initialLearningRate;
      }
docs: Sets the rate at which input is incorporated at each iteration of the SOM
  algorithm
  
  @param initialLearningRate the rate the SOM learns at