Introduction - If you have any usage issues, please Google them yourself
s1 is the M-file description of the SIMULINK system named s1.
The block-diagram can be displayed by typing: s1.
SYS=s1(T,X,U,FLAG) returns depending on FLAG certain
system values given time point, T, current state vector, X,
and input vector, U.
FLAG is used to indicate the type of output to be returned in SYS.