Modelling Lecture JP 08

8/2/2019 Modelling Lecture JP 08

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Lecture 07


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What we about to learn..

Content:

Basic Logical Functions

true and false Logicals

Loops: for Loop

Loops: while Loop

Loops: if Loop

Function


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Loops/Logicals 01 Sometime we would like to perform some repeated functions/routines in

programme, and we could use loops.

There are different type of logicals/loops, like

some basic ones: & and, | or, > greater than, (greater than): it is a function to express comparison of event with the

first greater than the second. =,


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Loops/Logicals 02 MATLAB represents the logicals oftrue or false by 1 or 0, respectively.

Logicals in statement-testing:>> a=1; a>2, a> b=[-1 2.2; 10 0];

>> b>=1 & b*3~=0

ans =

0 1

1 0


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Loops/Logicals 03 for loop expresses repeated statements for a specific number of times:

Example 1 (Single Layer):

>> y = -1:0.05:1;

>> for k = 1:8subplot(4,2,k), plot(y,sin(k*pi()*y))

end

Example 2 (Multiple Layers):

>> y = -1:0.05:1;

>> for i=4

for j=2

for k=1:8subplot(i,j,k), plot(y,sin(i*j*k*pi()*y));

end

end

end


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Loops/Logicals 04 for loop results:

Example 1 (Single Layer): Example 2 (Multiple Layers):

-1 -0.5 0 0.5 1-1

0

1

-1 -0.5 0 0.5 1-1

0

1

-1 -0.5 0 0.5 1-1

0

1

-1 -0.5 0 0.5 1-1

0

1

-1 -0.5 0 0.5 1-1

0

1

-1 -0.5 0 0.5 1-1

0

1

-1 -0.5 0 0.5 1-1

0

1

-1 -0.5 0 0.5 1-1

0

1

-1 -0.5 0 0.5 1-1

0

1

-1 -0.5 0 0.5 1-1

0

1

-1 -0.5 0 0.5 1-1

0

1

-1 -0.5 0 0.5 1-1

0

1

-1 -0.5 0 0.5 1-2

0

2x 10

-14

-1 -0.5 0 0.5 1-1

0

1

-1 -0.5 0 0.5 1-1

0

1

-1 -0.5 0 0.5 1-1

0

1


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Loops/Logicals 05 while loop expresses repeated statements for a infinity number of times:

Example:

>> dX=0.01;

>> X=0:dX:2;>> Y=0*X;

>> Y(1)=1;

>> i=1;S=size(X);

>> SM=max(size(X))

SM =

201

>> while(i> plot(X,Y)


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Loops/Logicals 06 while loop result:

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4


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Loops/Logicals 07 if loop expresses conditionally executed statements:

Example 1:

>> A=[1:4;1:4;1:4;1:4];

>> if A(1,2)==1A(1,1)=1;

elseif A(4,4)==2

A(3,3)=2;

else

A(1,1)=A(1,1)+1;

end

>> AA =

2 2 3 4

1 2 3 4

1 2 3 41 2 3 4


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Loops/Logicals 08 Combined-looping:

Example 2 (To Continue from 1st Example):

>> icount0=0;icount1=0;icount2=0;error=0;

>> for i=1:4for j=1:4

if A(i,j)==0

icount0=icount0+1;

elseif A(i,j)==1

icount1=icount1+1;

elseif A(i,j)==2

icount2=icount2+1;else

error=error+1;

end

endend


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Loops/Logicals 09 Example 2 (Continue As what results we can get):

>> icount0

icount0 =

0>> icount1

icount1 =

3

>> icount2

icount2 =

5

>> error

error =

8


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Loops/Logicals 10

Function a streams of simple operations that use for constructing

a routine/sub-routine:

In M-File, type:

function [X] = multiplication(x,y,z)k = x+y+z;

X = sqrt(k)*x*y*z;

Then, save under filename and folder you want: e.g.

multiplication.m

After that, we could execute:

H=multiplication(1,-2,3)

H =

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Modelling Lecture JP 08

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