Matlab

1
Matlab

• The language of technical computing

2
Outline

• Introduction

• C vs. Matlab

• Functions

• Graphing

• Matrix

• Image processing toolbox

• Neural network toolbox

• Menu

3
Introduction

• Things we like about Matlab

• Things we dont like about Matlab

4
Help
Help command
Help svd
5
C vs. Matlab
int j . for (j1jlt23jj2)
A4j3j
for i 12N for J 1N
A(I,J) (IJ-1) end end
6
C vs. Matlab (cont.)
int j while (jlt28) .
while Ngt 0, E E F
F AF/N N N 1 end
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C vs. Matlab (cont.)
If (ij) Aij2 else if
(abs(i-j)!1) .
if i j A(i,j) 2 elseif abs(i-j)
1 A(i,j) -1 else A(i,j)
0 end
8
C vs. Matlab (cont.)

• Index to an array can be zero.
• double, float , int
• is very important

• Index into matrix cant be negative or zero.
• Dont need to worry about the data type
• not so important

9
Functions
function mean,stdev stat(x) n length(x)
mean avg(x,n) stdev
function mean avg(x,n) mean sum(x)/n
double stat(double x) . return stdev
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Functions(cont.)
void Matrix2Vector( )

• function Matrix2Vector
• AvA(1,)
• for i2x
• AvAv A(i,)
• end
• AvAv'

11
Functions(cont.)
void AddF(int i) int main() addF(i) void
AddF(int i) ii1
File name testFunR.m
function testFun i2
AddF(i) i
function AddF(i)
ii1
A function declaration cannot appear within a
script M-file
12
Graphing
To make a graph of y sin(t) on the interval t
0 to t 10
In file PlotTest.m t 0.310 y sin(t)
plot(t,y,r)
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Graphing(cont.)
graphing the fuction z(x,y) x exp( - x2 - y2)
In file MeshTest.m x,y meshgrid (-2.22,
-2.22) z x . exp(-x.2 - y.2) mesh(z)
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Graphing(cont.)
Multiple windows in one figure
SubplotTest.m t 0.310 y sin(t) z
cos(t) subplot(2,1,1) plot(t,y)
subplot(2,1,2) plot(t,z)
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Graphing(cont.)
Multiple windows in one figure
SubplotTest.m t 0.310 y sin(t) z
cos(t) subplot(1,2,1) plot(t,y)
subplot(1,2,2) plot(t,z)
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Matrix
gtgt A1 2 33 2 1 A 1 2 3 3
2 1
gtgtbA(1,) b 1 2 3
gtgt BA' B 1 3 2 2 3 1
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Matrix Manipulation

• Singular value decomposition---U,S,Vsvd(A)

• Eigenvalues and eigenvectors---V,D eig(A)

• Orthogonal-triangular decomposition- Q,Rqr(A)

• LU factorization --L,U
  lu(A)

• Matrix rank --
  arank(A)

• Condition number -- acond(A)

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Image Processing Toolbox

• Read an image ---- Iimread(filename)

• Display an image ---- imshow(I)

• Write an image ---- imwrite(I,
  filename,FMT)

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Image Processing Toolbox(cont.)
ImageRWD.m function ImageTest Itifimread('image1.
tif') imwrite(Itif,'image1.bmp','bmp') Ibmpimre
ad('image1.bmp') subplot(1,2,1) imshow(Itif) su
bplot(1,2,2) imshow(Ibmp)
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Image Processing Toolbox(cont.)
EdgeTest.m function EdgeTest Itifimread('image1.t
if') Bedge(Itif,'canny') subplot
(1,2,1) imshow(Itif) subplot(1,2,2) imshow(B)
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Image Processing Toolbox(cont.)

• Pixel values and statistics --corr2,imhist

• Image enhancement histeq, medfilt2

• Linear filter -- conv2, filter2

• Image transform -- dct2, fft

• Binary image Op. --- dilate, erode

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Neural Network

• Feed-forward backpropagatoin

• Hopfield Networks

• Self-organizing maps

• Radial Basis networks

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Neural Networks(cont.)

• Create feed-forward NN

• Netnewff(-1 20 5,31,tansig,purelin,tr
  aingd)

• Neural Model tansig, logsig, purelin.

• Training method traingd, traingdm.

• Training

• net,trtrain(net,p,t)

• net.trainParam.???? show, lr, epochs,
  goal

• Simulation

• Asim(net,q)

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Menu
function MenuDemo cell_list fig_number
1 title_figure 'Menu Demo' cell_list1,1
'Plot','PlotTest' cell_list1,2
'Mesh','MeshTest' cell_list1,3
'Image','ImageRWD' cell_list1,4 'Image
Edge','EdgeTest' cell_list2,1
'????','PlotTest' cell_list2,2
'????','PlotTest' cell_list2,3
'????','PlotTest' cell_list2,4
'Exit','disp(''Bye. To run again, type
"menu".'') close(' num2str(fig_number)
')' show_window(cell_list,fig_number,title_fi
gure,120,20,3)
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Menu (cont.)

• cell_list1,1 name',function'

• show_window(cell_list,fig_number,title_figure,x,y,
  z)