More
MATLAB Commands...
On this page we present the
use of some very basic MATLAB commands and functions. With
Matlab, you can perform
simple operations, as if you were working with a calculator.
Operation 
Symbol 
Example 
Addition,
a+b 
+ 
5
+ 3 
Subtraction,
ab 
 
20  9 
Multiplication,
ab 
* 
8.7
* 9.2 
Division,
a/b 
/ 
40
/ 8 
Power,
a^{b} 
^ 
5^3

Common
Functions
abs(x) 
absolute value 
acos(x) 
inverse
cosine, result in radians 
angle(x) 
angle of
complex number 
asin(x) 
inverse sine,
result in radians 
atan(x) 
inverse tangent 
ceil(x) 
round towards
plus infinity 
conj(x) 
complex
conjugate 
cos(x) 
cosine 
exp(x) 
exponential 
fix(x) 
round towards
zero 
floor(x) 
round towards
minus infinity 
imag(x) 
complex
imaginary part 
log(x) 
natural
logarithm 
log10(x) 
common (base
10) logarithm 
real(x) 
complex real
part 
round(x) 
round towards
nearest integer 
sign(x) 
signum function 
sin(x) 
sine 
sqrt(x) 
square root 
tan(x) 
tangent 
Matlab
doesn't care about spaces between operands, and multiplications are
performed before additions. Type these operations on the command window
(only the
part just after '>>', and Matlab will give the answers):
>> 2 + 1 + 3
ans =
6
>> 8*9  6*5 + 3*4
ans =
54
>> x=2
x =
2
>> y=3
y =
3
>> cos(x)+sqrt(y)+tan(x+y)
ans =
2.0646
>>
You can keep values in variables:
>> apples=2
apples =
2
>> bananas=5
bananas =
5
>> peaches=4
peaches =
4
>> fruit=apples+bananas+peaches
fruit =
11
Ending the instruction with a ';' sign tells Matlab to make the
operation but not to display the answer.
To see a list of your variables in memory you can use the commands
'who' or 'whos'.
>> whos
Name 
Size 
Bytes 
Class 






ans 
1x1 
8 
double 
array 
apples 
1x1 
8 
double 
array 
bananas 
1x1 
8 
double 
array 
fruit 
1x1 
8 
double 
array 
peaches 
1x1 
8 
double 
array 
Grand total is 5 elements using 40 bytes
Variables are sensitive to lower/upper case. They have to start with a
letter and can contain also numbers and underscores.
Special
Names 
Value 
ans 
Default
for results 
pi 
3.141592... 
eps 
Smallest
possible number in Matlab 
inf 
Infinite 
NaN 
Not
a number 
i 
square
root of 1 
j 
square
root of 1 
To delete variables you can use the 'clear' command.
Operations with Complex
Numbers
>> c1 = 1  2i
c1 =
1.0000  2.0000i
>> c2 = 6  9j
c2 =
6.0000  9.0000i
>> c3 = sqrt(2)
c3 =
0 + 1.4142i
>> c4 = c1 + c2  c3
c4 =
7.0000 12.4142i
>>
Mfiles
Matlab
allows you to place your commands on a simple text file. You should
name this file with the '.m' extension. Giving Matlab the name of this
file while in the command window, makes Matlab to execute the script.
For example, name
a text file 'primer.m'.
Make it contain the following text:
a = 3; b = 4; c = 8;
d = a*bc
When you execute this from the command window
>> primer
you obtain this information from MATLAB:
d =
20
MFile
functions
disp(ans) 
show results
without showing the variable name 
input 
prompt for
user input 
keyboard 
stops
execution of the mfile and gives control to the
user's keyboard ('return' to quit) 
pause 
causes a
procedure to stop and wait for the user to
strike any key before continuing 
pause(n) 
pauses for n
seconds 
waitforbuttonpress 
wait for
key/buttonpress over figure 
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