check model的结果是simultaneous equations involving:births
population
births
check model的结果是simultaneous equations involving:deaths
population
deaths
我网上查了下,出现simultaneous equations involving是因为反馈回路中没有不包含状态变量,但我对流速变量的反馈回路进行检查的确是包含了population这个状态变量的啊!所以请高人指点!谢谢!