Transcript Embedded Communications in Wireless Sensor Network

Programming
Numerical Computing
with
.
MATLAB
for Scientists and Engineers
You will be able to



Write simple MATLAB programs using if
statement,
Write simple MATLAB programs using for
statement,
Convert a for-loop based program into a matrix
operation version.
2
Relational Operators

Operators
<

<=
>
>=
==
~=
Results are logicals
a = 5 < 8
b = [1:2:8] > 3
c = [2:2:13] == [ 0:3:17 ]
A = randint(3,4,10)
A>5
A(A>5) = 5
3
Exercise 1: Hate 4



Generate a 5x6 matrix A with random
integers between 0 and 10.
If some elements of matrix A is 4, replace it
with 0.
If some elements of matrix A is odd, subtract
1 from the elements.
hate4.m
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Logical Operators

Operators
&


|
~
Built-in Functions
and(A,B)
or(A,B)
not(A)
xor(A,B)
all(A)
any(A)
find(A)
find(A>d)
Examples
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Conditional Statement: if

if condition

n = input('Enter an integer: ');
if mod(n,2)
S1 fprintf('%d is an odd
integer.\n', n );
end
x<0
T
S1
F
if condition – else
x<0
F
T
S1
S2
n = input('Enter an integer: ');
if mod(n,2)
S1 fprintf('%d is an odd
integer.\n', n );
else
S2 fprintf('%d is an even
integer.\n', n );
end
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Exercise 2 Volume in a Water Tank

Find the volume of the water tank below
when the depth is h.
10m
8m
8m
hm
8m
6m
6m
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Solution 2

Function m-file
water_volume.m

Commands
8
if – elseif – else – end

Nested If
if A
x = a
else
if B
x = b
else
if C
x = c
else
x = d
end
end
end
if A
x = a
elseif B
x = b
elseif C
x = c
else
x = d
end
F
if
T
S1
elseif
F
elseif
T
T
S2
S3
F
S4
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For Loops
for n=a:b
statements
end
i=0;
for t=0:0.1:100
i = i+1;
x(i) = sin(2*pi*200*t);
end
for n=1:5
for m=5:-1:1
a(n,m)=n^2 + m^2;
end
end
t=0:0.1:100;
x = sin(2*pi*200*t);
n=1:5;
m=1:5;
[nn,mm]=meshgrid(n,m);
a=nn.^2 + mm.^2;
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Example

Taylor series of sine function
(1)k x 2 k 1
sin x  
k 0 (2k  1)!


Write a function y= Tsin(x,n), which is the
partial sum of n-terms.
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Exercise 3

Taylor series of exp(x).

Write a function y= Texp(x,n), which is the
partial sum of n-terms. Use Texp() to plot
exp(x), Texp(x,5), Texp(x,10), Texp(x,100).
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Solution 3

Function m-file
Texp.m

Commands and Screenshot
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While Loops
i=0;t=0;
while t<=100
i = i+1;
x(i) = sin(2*pi*200*t);
t = t+0.1;
end
i=0;
for t=0:0.1:100
i = i+1;
x(i) = sin(2*pi*200*t);
end
t=0:0.1:100;
x = sin(2*pi*200*t);
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Lotto Numbers
disp('I generate Lotto numbers');
disp('Good Luck!');
B=[];
for i=1:5
L=0;
while L ~= 6,
fprintf('Try - %d \n ', i );
A=floor(rand(1,6)*45)+1;
A=unique(A);
L=length(A);
end
B(i,:) = A;
pause(1);
end
B
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Branch
apple=100;
if apple < 5
disp('few');
elseif apple < 20
disp('a few');
else
disp('a lot');
end
mon = 10;
switch mon
case 1
month = 'January';
case 2
month = 'February';
otherwise
month = 'Others';
end
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Branch
x = 2.7;
units = 'm';
switch units
case {'inch', 'in'}
y = x * 2.54;
case {'feet', 'ft'}
y = x * 2.54 * 12;
case {'meter', 'm'}
y = x * 100;
case {'milimeter', 'mm'}
y = x / 10;
case {'centimeter', 'cm'}
y = x;
otherwise
y = nan;
end
Unlike C,
no break!
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