I was teaching myself standing wave's chapter. It is said in the book that when plucking in the center of the string, it will cause two traveling waves of different directions, one left, one right. Then both of them will reach ends of string and invert back. Before they encounter at the center, they will form standing waves at left part and right part. However, if we combine them into a complete image, it is different from normal standing wave pattern. What's more, it seems that the problem will continue because it is just like a cycle, the left part and right part always appear to be symmetrical instead like normal standing wave. (I have attached a detailed process from 0-2T.) Anyone could help me?