Glossary
We present here the most commonly used MATLAB objects in six categories:
operators, built-in constants, built-in functions, commands, graphics com-
mands, and MATLAB programming constructs. Though MATLAB does
not distinguishbetween commands and functions, it is convenient to think
of a MATLAB function as we normally think of mathematical functions. A
MATLAB function is something that can be evaluated or plotted; a com-
mand is something that manipulates data or expressions or that initiates a
process.
We list each operator, function, and command together with a short
description of its effect, followed by one or more examples. Many MATLAB
commands can appear in a number of different forms, because you can apply
them to different kinds of objects. In our examples, we have illustrated the
most commonly used forms of the commands. Many commands also have nu-
merous optional arguments; in this glossary, we have only included some very
common options. You can find a full description of all forms of a command,
and get a more complete accounting of all the optional arguments available
for it, by reading the help text — which you can access either by typing help
<commandname> or by invoking the Help Browser, shown in Figure G-1.
This glossary does not contain a comprehensive list of MATLAB commands.
We have selected the commands that we feel are most important. You can find
a comprehensive list in the Help Browser. The Help Browser is accessible
from the Command Window by typing helpdesk or helpwin, or from the
LaunchPad window in your Desktop under MATLAB : Help. Exactly what
commands are covered in your documentation depends on your installation, in
particular which toolboxes and what parts of the overall documentation files
you installed.
☞
Se e Online Help in Chapter 2 for a detailed description of the Help Browser.
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300

’ Complex conjugate transpose of a matrix. See ctranspose. Also delimits the
beginning and end of a string.
; Suppresses output of a MATLAB command, and can be used to separate commands
on a command line. Also used to separate the rows of a matrix or column vector.
X = 0:0.1:30;
[1; 2; 3]
, Separates elements of a row of a matrix, or arguments to a command. Can also be
used to separate commands on a command line.
.’ Transpose of a matrix. See transpose.
... Line continuation operator. Cannot be used inside quoted strings. Type help
punct for more information.
1+3+5+7+9+11...
+13+15+17
[’This is a way to create very long strings ’, ...
’that span more than one line. Note the square brackets.’]
! Run command from operating system.
!C:
\
Programs
\
program.bat
% Comment. MATLAB will ignore the rest of the same line.
@
Creates a function handle.
fminbnd(@cos, 0, 2*pi)
Built-in Constants
eps Roughly the size of the computer’s floating point round-off error; on most
computers it is around 2 × 10
−16
.

−t
2
dt.
exp e
x
.
expm Matrix exponential.
gamma The gamma function (x) =

∞
0
e
−t
t
x−1
dt (when Re x > 0). The property
(k+ 1) = k!, for nonnegative integers k, is sometimes useful.
imag imag(z), the imaginary part of a complex number.
log The natural logarithm ln x = log
e
x.
real real(z), the real part of a complex number.
sec sec x.
sech sech x.
sign Returns −1, 0, or 1, depending on whether the argument is negative, zero, or
positive.
sin sin x.
sinh sinh x.
sqrt
√

compose Composition of functions.
syms x y; f = exp(x); g = sin(y); h = compose(f, g)
ctranspose Conjugate transpose of a matrix. Usually invoked withthe ’ operator.
Equivalent to transpose for real matrices.
A=[13i]
A’
D Not a true MATLAB command. Used in dsolve to denote differentiation. See diff.
dsolve(’x*Dy + y = sin(x)’, ’x’)
delete Deletes a file.
delete <filename>
det The determinant of a matrix.
det([1 3; 4 5])
diag Gives a square matrix witha prescribed diagonal vector, or picks out the
diagonal in a square matrix.
V = [2 3 4 5]; diag(V)
X = [2 3; 4 5]; diag(X)
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Glossary
diary Writes a transcript of a MATLAB session to a file.
diary <filename>
diary off
diff Symbolic differentiation operator (also difference operator).
syms x; diff(xˆ3)
diff(’x*yˆ2’, ’y’)
dir Lists the files in the current working directory. Similar to ls.
disp Displays output without first giving its name.
x = 5.6; disp(x)
syms x; disp(xˆ2)
disp(’This will print without quotes.’)
double Gives a double-precision value for either a numeric or symbolic quantity.

find Finds the indices of nonzero elements of a vector or matrix.
X = [2 0 5]; find(X)
fminbnd Finds the smallest (approximate) value of a function over an interval.
fminbnd(’xˆ4 - xˆ2 + 1’, 0, 1)
f = inline(’xˆ3 - 7*xˆ2 - 5*x + 2’, ’x’); fminbnd(f, 4, 6)
format Specifies the output format for numerical variables.
format long
fzero Tries to find a zero of the specified function near a given starting point or on
a specified interval.
fzero(inline(’cos(x) - x’), 1)
fzero(@cos, [-pi 0])
guide Opens the GUI Design Environment.
guide mygui
help Asks for documentation for a MATLAB command. See also lookfor.
help factor
inline Constructs a MATLAB inline function from a string expression.
f = inline(’xˆ5 - x’); f(3)
sol = dsolve(’Dy = xˆ2 + y’, ’y(0) = 2’, ’x’);
fsol = inline(vectorize(sol), ’x’)
int Integration operator for bothdefinite and indefinite integrals.
int(’1/(1 + xˆ2)’, ’x’)
syms x; int(exp(-x), x, 0, Inf)
inv Inverse of a square matrix.
inv([1 2; 3 5])
jacobian Computes the Jacobian matrix, or for a scalar function, the symbolic gra-
dient.
syms x y; f = xˆ2*yˆ3; jacobian(f)
306
Glossary
length Returns the number of elements in a vector or string.

Q
to abort
the output.
more on
more off
notebook Opens an M-book (Windows only).
notebook problem1.doc
notebook -setup
Glossary
307
num2str Converts a number to a string. Useful in programming.
constant = [’a’ num2str(1)]
ode45 Numerical ODE solver for first-order equations. See MATLAB’s online help
for ode45 for a list of other MATLAB ODE solvers.
f = inline(’tˆ2 + y’, ’t’, ’y’)
[x, y] = ode45(f, [0 10], 1);
plot(x, y)
ones Creates a matrix of ones.
ones(3)
ones(3, 1)
open Opens a file. The way this is done depends on the filename extension.
open myfigure.fig
path Without an argument, displays the search path. With an argument, sets the
searchpath. Type help path for details.
pretty Displays a symbolic expression in a more readable format.
syms x y; expr = x/(x - 3)/(x + 2/y)
pretty(expr)
prod Computes the product of the entries of a vector.
X=[351-623-56100]; prod(X)
pwd Shows the name of the current (working) directory.

sound Plays a vector through the computer speakers.
sound(sin(0:0.1*pi:1000*pi))
strcat Concatenates two or more strings.
strcat(’This ’, ’is ’, ’a ’, ’long ’, ’string.’)
str2num Converts a string to a number. Useful in programming.
constant = ’a7’
index = str2num(constant(2))
subs Substitutes for parts of an expression.
subs(’xˆ3 - 4*x + 1’, ’x’, 2)
subs(’sin(x)ˆ2 + cos(x)’, ’sin(x)’, ’z’)
sum Sums a vector, or sums the columns of a matrix.
k = 1:10; sum(k)
sym Creates a symbolic variable or number.
sym pi
x = sym(’x’)
constant = sym(’1/2’)
syms Shortcut for creating symbolic variables. The command syms x is
equivalent to x = sym(’x’).
symsxyz
Glossary
309
symsum Performs a symbolic summation of a vector, possibly withinfinitely many
entries.
symsxkn;symsum(xˆk, k, 0, n)
syms n; symsum(nˆ(-2), n, 1, Inf)
taylor Gives a Taylor polynomial approximation of a specified order (the default is
5) at a specified point (default is 0).
syms x; taylor(cos(x), 8, 0)
taylor(exp(1/x), 10, Inf)
transpose Transpose of a matrix (compare ctranspose). Converts a column vector