说明：  Q波和S波通常是低幅高频波，一般Q波位于S波之前，S波位于R波之后 ，由于他们是一般向下的波，所以他们的峰值点和极值是对应的。因次在检测到R波向左和向右分别搜寻到极值点，对应的就是Q波和S波。而现在我们只需要检测到R波，所以就不需要检测Q波与S波的极值点了。
(Q-wave and S-wave amplitude high-frequency waves are usually low, generally located before the Q-wave S-wave, S-wave is located after the R-wave, because they are generally downward wave, so their peak point and the extreme is the corresponding. Dimensionless detected R-wave to the left and right were searched extreme points, the corresponding Q-wave and S-wave is. And now we just need to detect the R-wave, so you do not need to detect extreme point Q wave and the S wave.)