[zimu554]

问题：
Derivative input 1 of 'fangzheng/equ2/sita1' at time 0 is Inf or NaN. Stopping simulation. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances).

始终没有找出解决的办法！请高手指点！！！