Control package

The control package is part of the Octave Forge project.

Function list

Linear System Representation

Chapter	Function	Implemented	File	Status
Basic Models	tf	yes	@tf/tf.m
	zpk	yes	zpk.m
	ss	yes	@ss/ss.m
	frd	yes	@frd/frd.m
	pid	no
	pidstd	no
	pid2	no
	dss	yes	@lti/dss.m
	drss	no
	filt	yes	filt.m
	rss	no
Tunable Models	ltiblock.gain	no
	ltiblock.pid	no
	ltiblock.pid2	no
	ltiblock.ss	no
	ltiblock.tf	no
	realp	no
	AnalysisPoint	no
	genss	no
	genfrd	no
	genmat	no
	getLoopTransfer	no
	getIOTransfer	no
	getSensitivity	no
	getCompSensitivity	no
	getPoints	no
	replaceBlock	no
	getValue	no
	setValue	no
	getBlockValue	no
	setBlockValue	no
	showBlockValue	no
	showTunable	no
	nblocks	no
	getLFTModel	no
Model with Time Delays	pade	no
	absorbDelay	no
	thiran	yes	thiran.m
	hasdelay	no
	hasInternalDelay	no
	totaldelay	no
	delayss	no
	setDelayModel	no
	getDelayModel	no
Model Attributes	get	yes	@iddata/get.m
	set	yes	@iddata/set.m
	tfdata	yes	@lti/tfdata.m
	zpkdata	yes	@lti/zpkdata.m
	ssdata	yes	@lti/ssdata.m
	frdata	yes	@lti/frdata.m
	piddata	no
	pidstddata	no
	piddata2	no
	pidstddata2	no
	dssdata	yes	@lti/dssdata.m
	chgFreqUnit	no
	chgTimeUnit	no
	isct	yes	@lti/isct.m
	isdt	yes	@lti/isdt.m
	isempty	yes	built-in function
	isfinite	yes	built-in function
	isParametric	no
	isproper	no
	isreal	yes	built-in function
	isiso	no
	isstable	yes	@lti/isstable.m
	isstatic	no
	order	no
	ndims	yes	built-in function
	size	yes	built-in function
Model Arrays	stack	no
	nmodels	no
	permute	yes	built-in function
	reshape	yes	built-in function
	repsys	yes	repsys.m

Some very basic examples

PT1/low-pass filter step response

Code: Creating a transfer function and plotting its response

T1=0.4; # time constant P=tf([1], [T1 1]) # create transfer function model step(P,2) # plot step response #add some common markers like the tangent line at the origin, which crosses lim(n->inf) f(t) at t=T1 hold on plot ([0 T1], [0 1],"g") plot ([T1 T1], [0 1],"k") plot ([0 T1], [1-1/e 1-1/e],"m") hold off

Try also bode(P)! (a first order low-pass filter has -3db magnitude at f=1/T1)