[sys] output.

Hi,

How do we distinguish between different outputs [sys] of the functions in Matlab level 1 s-function? I have sys=u(i); and I want to use it an input in a different function..

Answer 1

[Kaustubha Govind]

Since Level-1 S-functions have long been deprecated, and only exist for the sake of backward compatibility, there is not a lot of published documentation on them (if you are writing a new S-function, please consider writing it as a Level-2 S-function). However, if you are maintaining an existing level-1 S-function and want to understand what the return value (sys) means for each flag, type this command in MATLAB:

   >> help sfuntmpl

There is a bunch of information. In particular, the part that you are asking about is as follows:

    What is returned by SFUNC at a given point in time, T, depends on the
    value of the FLAG, the current state vector, X, and the current
    input vector, U.

    FLAG   RESULT             DESCRIPTION
    -----  ------             --------------------------------------------
    0      [SIZES,X0,STR,TS]  Initialization, return system sizes in SYS,
                              initial state in X0, state ordering strings
                              in STR, and sample times in TS.
    1      DX                 Return continuous state derivatives in SYS.
    2      DS                 Update discrete states SYS = X(n+1)
    3      Y                  Return outputs in SYS.
    4      TNEXT              Return next time hit for variable step sample
                              time in SYS.
    5                         Reserved for future (root finding).
    9      []                 Termination, perform any cleanup SYS=[].