confused with gradients of center loss

[Siqing1996]

1. diff = diff / tf.cast((1 + appear_times), tf.float32)
2. diff = alpha * diff
3. centers_update_op = tf.scatter_sub(centers, labels, diff)
   您好，有个疑问，第一行代码，根据论文中给的公式应该是 diff = （diff * appear_times）/ tf.cast((1 + appear_times), tf.float32)？