The data structure elements (and variable types) common to all system
representations are listed below; examples of the initialization
and use of the system data structures are given in subsequent sections and
in the online demo
This vector indicates both what representation was used to initialize the system data structure (called the primary system type) and which other representations are currently up-to-date with the primary system type (see structaccess).
The value of the first element of the vector indicates the primary system type.
The next three elements are boolean flags that indicate whether tf, zp,
or ss, respectively, are “up to date" (whether it is safe to use the
variables associated with these representations). These flags are
changed when calls are made to the
indicates which outputs are discrete time (i.e., produced by D/A converters) and which are continuous time. yd(ii) = 0 if output ii is continuous, = 1 if discrete.
The remaining variables of the system data structure are only present
if the corresponding entry of the
sys vector is true (=1).