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This function changes the sampling time (tsam) of the system. Exits with an error if sys is purely continuous time.
return the number of states, inputs, and/or outputs in the system sys.
Inputs
- sys
- system data structure
- opt
- String indicating which dimensions are desired. Values:
"all"
- (default) return all parameters as specified under Outputs below.
"cst"
- return n= number of continuous states
"dst"
- return n= number of discrete states
"in"
- return n= number of inputs
"out"
- return n= number of outputs
Outputs
- n
- number of continuous states (or individual requested dimension as specified by opt).
- nz
- number of discrete states
- m
- number of system inputs
- p
- number of system outputs
- yd
- binary vector; yd(ii) is nonzero if output ii is discrete. yd(ii) = 0 if output ii is continous
Get signal names from a system
Inputs
- sys
- system data structure for the state space system
- sigid
- signal id. String. Must be one of
"in"
- input signals
"out"
- output signals
"st"
- stage signals
"yd"
- value of logical vector yd
- signum
- index(indices) or name(s) or signals; see
sysidx
- strflg
- flag to return a string instead of a cell array; Values:
0
- (default) return a cell array (even if signum specifies an individual signal)
1
- return a string. Exits with an error if signum does not specify an individual signal.
Outputs
- •If sigid is not specified:
- stname
- inname
- outname
- signal names (cell array of strings); names of states, inputs, and outputs, respectively.
- yd
- binary vector; yd(ii) is nonzero if output ii is discrete.
- •If sigid is specified but signum is not specified:
sigid="in"
- siglist is set to the cell array of input names.
sigid="out"
- siglist is set to the cell array of output names.
sigid="st"
- siglist is set to the cell array of state names.
stage signals
sigid="yd"
- siglist is set to logical vector indicating discrete outputs; siglist(ii) = 0 indicates that output ii is continuous (unsampled), otherwise it is discrete.
- •If the first three input arguments are specified:
- signame is a cell array of the specified signal names (sigid is
"in"
,"out"
, or"st"
), or else the logical flag indicating whether output(s) signum is(are) discrete (sigval=1) or continuous (sigval=0).Examples (From
sysrepdemo
)octave> sys=ss(rand(4),rand(4,2),rand(3,4)); octave># get all signal names octave> [Ast,Ain,Aout,Ayd] = sysgetsignals(sys) Ast = ( [1] = x_1 [2] = x_2 [3] = x_3 [4] = x_4 ) Ain = ( [1] = u_1 [2] = u_2 ) Aout = ( [1] = y_1 [2] = y_2 [3] = y_3 ) Ayd = 0 0 0 octave> # get only input signal names: octave> Ain = sysgetsignals(sys,"in") Ain = ( [1] = u_1 [2] = u_2 ) octave> # get name of output 2 (in cell array): octave> Aout = sysgetsignals(sys,"out",2) Aout = ( [1] = y_2 ) octave> # get name of output 2 (as string): octave> Aout = sysgetsignals(sys,"out",2,1) Aout = y_2
return the initial system type of the system
Input
- sys
- System data structure.
Output
- systype
- String indicating how the structure was initially constructed. Values:
"ss"
,"zp"
, or"tf"
.FIR initialized systems return
systype="tf"
.
change the names of selected inputs, outputs and states.
Inputs
- sys
- System data structure.
- opt
- Change default name (output).
"out"
- Change selected output names.
"in"
- Change selected input names.
"st"
- Change selected state names.
"yd"
- Change selected outputs from discrete to continuous or from continuous to discrete.
- names
opt = "out", "in", "st"
- string or string array containing desired signal names or values.
opt = "yd"
- To desired output continuous/discrete flag. Set name to 0 for continuous, or 1 for discrete.
- sig_idx
- indices or names of outputs, yd, inputs, or states whose respective names/values should be changed.
Default: replace entire cell array of names/entire yd vector.
Outputs
- retsys
- sys with appropriate signal names changed (or yd values, where appropriate).
Example
octave:1> sys=ss([1 2; 3 4],[5;6],[7 8]); octave:2> sys = syssetsignals(sys,"st",str2mat("Posx","Velx")); octave:3> sysout(sys) Input(s) 1: u_1 Output(s): 1: y_1 state-space form: 2 continuous states, 0 discrete states State(s): 1: Posx 2: Velx A matrix: 2 x 2 1 2 3 4 B matrix: 2 x 1 5 6 C matrix: 1 x 2 7 8 D matrix: 1 x 1 0
Update the internal representation of a system.
Inputs
- sys:
- system data structure
- opt
- string:
"tf"
- update transfer function form
"zp"
- update zero-pole form
"ss"
- update state space form
"all"
- all of the above
Outputs
- retsys
- Contains union of data in sys and requested data. If requested data in sys is already up to date then retsys=sys.
Conversion to tf or zp exits with an error if the system is mixed continuous/digital.
Determines the type of system matrix. inmat can be a varying, a system, a constant, and an empty matrix.
Outputs
- systype
- Can be one of: varying, system, constant, and empty.
- nout
- The number of outputs of the system.
- nin
- The number of inputs of the system.
- ncstates
- The number of continuous states of the system.
- ndstates
- The number of discrete states of the system.