into small numbers e g 0 5 and select a practice ratio a gt 0 default practice ratio is set at 0 02 with a certain practice frequency to be determined input pairs of the practice patterns in sequence and change the interface strength values as follows a sigmoid function is used as an activation function a unipolar sigmoid function a most commonly used function in a neural network model can be expressed as shown in the mathematical formula 3 since a unipolar sigmoid function expressed in the mathematical formula 3 is used as an activation function related output values will be between 0 and 1 if the u2018 net u2019 value equals to 0 then an output value of a neuron becomes u00bd as u2018 u03bb u2019 increases u2018 f net u2019 value gets closer to a y axis if u2018 u03bb u2019 u2192 u221e then the sigmoid function shows certain step function characteristics as shown in the mathematical formula 4 u2018 u03bb u2019 1 was used the formula above can be re arranged as follows loaded sum of the hidden layers u2018 net z u2019 and output value u2018 z u2019 can be expressed as shown in the mathematical formula 7 loaded sum of the output layers u2018 net y u2019.