Problem solved. It was because the normalization: A = (2*A2-max_a-min_a)/(max_a-min_a). I forgot to add a small value to the denominator henceforth division by zero occurred. 
Problem solved. It was because the normalization: A = (2*A2-max_a-min_a)/(max_a-min_a). I forgot to add a small value to the denominator henceforth division by zero occurred.