Verlet的集成让我的物理引擎崩溃

I'm building a physics engine and i had some sort of "pseudo-verlet" thing going and i wanted to upgrade it to "real" verlet. So i found an article and set to work. After i added what i think is a good approximation, the engine doesn't work anymore. Can someone help me understand what i'm doing wrong?I'm building a physics engine and i had some so