Introduction to
Programming in
MATLAB
Intro. MATLAB Peer Instruction Lecture Slides by Dr. Cynthia Lee, UCSD is licensed under
a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
Based on a work at www.peerinstruction4cs.org.
1
A number by any other name wouldn’t smell as sweet?
VARIABLE NAMES
2
Which of these is NOT a legal variable
name in MATLAB?
a)
b)
c)
d)
e)
_factors_of_48_
my_factors
factor
f
None or more than one of the above
3
An important programming language concept called
“scope” refers to the process for managing names, and
how to resolve conflicts where different things have the
same name. We’ll talk more about this later, but for
now just something you should be aware of.
4
Computer scientists call words/text/sentences/punctuation “strings”
STRINGS IN MATLAB
5
Strings in MATLAB
• Remember: to a computer, EVERYTHING is numbers
– Numbers, letters, words, punctuation, images, video,
sound
– Even computer programs themselves!
• In your lab, you got MATLAB to “reveal” to you its
code numbers that it associates with each character
in a string
– ‘a’ = 97, ‘b’ = 98, …
• This character code is a widely-used code called
ASCII
– Next slide gives part of the ASCII code (the whole thing
goes from 0 to 255, next slide shows only 32 to 126) 6
32
[space]
56
8
80
P
104
h
33
!
57
9
81
Q
105
i
34
"
58
:
82
R
106
j
35
#
59
;
83
S
107
k
36
$
60
<
84
T
108
l
37
%
61
=
85
U
109
m
38
&
62
>
86
V
110
n
39
'
63
?
87
W
111
o
40
(
64
@
88
X
112
p
41
)
65
A
89
Y
113
q
42
*
66
B
90
Z
114
r
43
+
67
C
91
[
115
s
44
,
68
D
92
\
116
t
45
-
69
E
93
]
117
u
46
.
70
F
94
^
118
v
47
/
71
G
95
_
119
w
48
0
72
H
96
`
120
x
49
1
73
I
97
a
121
y
50
2
74
J
98
b
122
z
51
3
75
K
99
c
123
{
52
4
76
L
100
d
124
|
53
5
77
M
101
e
125
}
54
6
78
N
102
f
126
~
7
55
7
79
O
103
g
ASCII
code
(excerpt
from 32
to 126)
Which of the following is the result of
running this code:
>> foo = 'I can't wait to learn more about
MATLAB!' + 1
a) The value of the variable foo will be set to equal the
string, and it will print
foo =
'I can't wait to learn more about MATLAB!'
b) Several numbers will be printed (one for each character
in the string)
c) MATLAB will give an error
8
Text messages from inside the belly of the beast—just like real text
messages with their LOLZ, BRB, IKWYM, IDK, TTYL, program errors require
some clues to interpret.
INTERPRETING MATLAB ERRORS
9
Which of these shows the outcome
when “factor(16+) + 3” is typed?
>> factor(16+) + 3
(a)
??? factor(16+) + 3
Error: Unbalanced or unexpected parenthesis or bracket.
>> factor(16+) + 3
??? factor(16+) + 3
(b)
|
Error: Unbalanced or unexpected parenthesis or bracket.
>> factor(16+) + 3
??? factor(16+) + 3
(c)
|
Error: Unbalanced or unexpected parenthesis or bracket.
10
What does the 24 refer to in this error
message?
>> factor(48.001)
??? Error using ==> factor at 24
N must be a nonnegative integer.
a) It doesn’t refer to anything—just jibberish
b) 48.001 is the argument, and 2 * 24 is 48, so it’s
a number you encounter when factoring 48
c) It is a location in the code for the factor
function
d) None or more than one of the above
11