请教ode求解微分方程组的问题

sky8754180

用matlab中的ode函数求解形如y'=f(t,y)的函数，计算中途终止，并提示：
??? Error using ==> odearguments at 137
Inputs must be floats, namely single or double.
Error in ==> ode45 at 173
[neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0,
odeArgs, odeFcn, ...
Error in ==> simplified_model_8 at 357
[T,Y]=ode45(odefun,tspan,y0);%时间选择0.1s,Warning: Matrix
is singular, close to singular or badly scaled. Results
may be inaccurate. RCOND = NaN.

哪位兄弟遇到过这样的问题，望指教，谢谢！