Matlab Commands List

The following list of commands can be very useful for future reference. Use "help" in Matlab for more information on how to use the commands.

In these tutorials, we use commands both from Matlab and from the Control Systems Toolbox, as well as some commands/functions which we wrote ourselves. For those commands/functions which are not standard in Matlab, we give links to their descriptions. For more information on writing Matlab functions.

Note:Matlab commands from the control system toolbox are highlighted in red.
Non-standard Matlab commands are highlighted in green.

Command	Description
abs	Absolute value
acker	Compute the K matrix to place the poles of A-BK, see also place
axis	Set the scale of the current plot, see also plot, figure
bode	Draw the Bode plot, see also logspace, margin, nyquist1
c2dm	Continuous system to discrete system
clf	Clear figure (use clg in Matlab 3.5)
conv	Convolution (useful for multiplying polynomials), see also deconv
ctrb	The controllability matrix, see also obsv
deconv	Deconvolution and polynomial division, see also conv
det	Find the determinant of a matrix
dimpulse	Impulse response of discrete-time linear systems, see also dstep
dlqr	Linear-quadratic requlator design for discrete-time systems, see also lqr
dlsim	Simulation of discrete-time linear systems, see also lsim
dstep	Step response of discrete-time linear systems, see also stairs
eig	Compute the eigenvalues of a matrix
eps	Matlab's numerical tolerance
feedback	Feedback connection of two systems.
figure	Create a new figure or redefine the current figure, see also subplot, axis
for	For, next loop
format	Number format (significant digits, exponents)
function	Creates function m-files
grid	Draw the grid lines on the current plot
gtext	Add a piece of text to the current plot, see also text
help	HELP!
hold	Hold the current graph, see also figure
if	Conditionally execute statements
imag	Returns the imaginary part of a complex number, see also real
impulse	Impulse response of continuous-time linear systems, see also step, lsim, dlsim
input	Prompt for user input
inv	Find the inverse of a matrix
jgrid	Generate grid lines of constant damping ratio (zeta) and settling time (sigma), see also sgrid, sigrid, zgrid
legend	Graph legend
length	Length of a vector, see also size
linspace	Returns a linearly spaced vector
lnyquist1	Produce a Nyquist plot on a logarithmic scale, see also nyquist1
log	natural logarithm, also log10: common logarithm
loglog	Plot using log-log scale, also semilogx/semilogy
logspace	Returns a logarithmically spaced vector
lqr	Linear quadratic regulator design for continuous systems, see also dlqr
lsim	Simulate a linear system, see also step, impulse, dlsim.
margin	Returns the gain margin, phase margin, and crossover frequencies, see also bode
norm	Norm of a vector
nyquist1	Draw the Nyquist plot, see also lnyquist1. Note this command was written to replace the Matlab standard command nyquist to get more accurate Nyquist plots.
obsv	The observability matrix, see also ctrb
ones	Returns a vector or matrix of ones, see also zeros
place	Compute the K matrix to place the poles of A-BK, see also acker
plot	Draw a plot, see also figure, axis, subplot.
poly	Returns the characteristic polynomial
polyadd	Add two different polynomials
polyval	Polynomial evaluation
print	Print the current plot (to a printer or postscript file)
pzmap	Pole-zero map of linear systems
rank	Find the number of linearly independent rows or columns of a matrix
real	Returns the real part of a complex number, see also imag
rlocfind	Find the value of k and the poles at the selected point
rlocus	Draw the root locus
roots	Find the roots of a polynomial
rscale	Find the scale factor for a full-state feedback system
set	Set(gca,'Xtick',xticks,'Ytick',yticks) to control the number and spacing of tick marks on the axes
series	Series interconnection of Linear time-independent systems
sgrid	Generate grid lines of constant damping ratio (zeta) and natural frequency (Wn), see also jgrid, sigrid, zgrid
sigrid	Generate grid lines of constant settling time (sigma), see also jgrid, sgrid, zgrid
size	Gives the dimension of a vector or matrix, see also length
sqrt	Square root
ss	Create state-space models or convert LTI model to state space, see also tf
ss2tf	State-space to transfer function representation, see also tf2ss
ss2zp	State-space to pole-zero representation, see also zp2ss
stairs	Stairstep plot for discreste response, see also dstep
step	Plot the step response, see also impulse, lsim, dlsim.
subplot	Divide the plot window up into pieces, see also plot, figure
text	Add a piece of text to the current plot, see also title, xlabel, ylabel, gtext
tf	Creation of transfer functions or conversion to transfer function, see also ss
tf2ss	Transfer function to state-space representation, see also ss2tf
tf2zp	Transfer function to Pole-zero representation, see also zp2tf
title	Add a title to the current plot
wbw	Returns the bandwidth frequency given the damping ratio and the rise or settling time.
xlabel/ylabel	Add a label to the horizontal/vertical axis of the current plot, see also title, text, gtext
zeros	Returns a vector or matrix of zeros
zgrid	Generates grid lines of constant damping ratio (zeta) and natural frequency (Wn), see also sgrid, jgrid, sigrid
zp2ss	Pole-zero to state-space representation, see also ss2zp
zp2tf	Pole-zero to transfer function representation, see also tf2zp