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EE 20N Matlab Function Description

Lab 02

15 Feb 2005

v=[1:64];
image(v);
//generate a default gradient image

map=colormap
//to see colormap numerically

size(map)
//ans =     1     3
//to verify the size of the map
//Notice that it has 64 rows and three columns. Each row is one entry
in the colormap. The three
columns give the amounts of red, green, and blue respectively in the
colormap.
//These amounts range
from 0 (none of the color present) to 1.0 (the maximum amount of the
color possible).

map=gray(256);
colormap(map);
//generate a plain gray
image([1:256]);
//generate a gray gradient

map=white(256);

axis image
//force matlab not to stretch

cd U:
cd lab02
//change to directory

imfinfo('helen.jpg')
//get image information

helen=imread('helen.jpg');
//image read
image(helen);
//display image in a stretched version
axis image
//display image in the original dimension

whos
//display info of everything in the workspace

pixel = helen(1,1,:)
//upper left pixel of the image (3 basic colors)
//looks like bright color is high number, dark color is small number

whos helen
//display the array information

rgb=squeeze(pixel)
//squeeze the info for array of length one
 

Lab 01

help size
//to get help for the function size

array =[1 2 3 4 5]
//array = 1x5, row vector

array = [1:5]
//array = 1x5, row vector

array = 1:5
//array = 1x5, row vector

array = [1:1:5]
//array = 1x5, row vector

array = [1:-1:-5]
//array = 1x7, row vector

array = [start:step:stop]

array = [1 2; 3 4]
//array = 2x2, matrix

array = [1; 2; 3; 4]
//array = 4x1, column vector

size(array)
//size of array as [M, N]

array = zeros(3)
//an 3-by-3 matrix of zeros.
array = zeros(N)
//an N-by-N matrix of zeros.
//ZEROS(M,N) or ZEROS([M,N]) is an M-by-N matrix of zeros.
array = ones(3)
//an 3-by-3 matrix of 1s.
array = ones(N)
//an N-by-N matrix of 1s.
//ONES(M,N) or ONES([M,N]) is an M-by-N matrix of ones.

array = eye(3)
//an 3-by-3 matrix of diagonal matrix.
array = eye(N)
//an N-by-N matrix of diagonal matrix.
//EYE(M,N) or EYE([M,N])

array= 1:1:4
//array = 1 2 3 4

>> start =1;
>> stop=5;
>> step=1;
>> array=start:step:stop;
>> length(array)
//ans = 5

array = [1 2 3; 4 5 6]
eye2 = eye(2)

>> round (array)

>> sin(pi/4)

>> sin([0 pi/4 pi/2 3*pi/4 pi])

>> [1 2 3 4].*[1 2 3 4]

>> sin([0 pi/4 pi/2 3*pi/4 pi]) .* sin([0 pi/4 pi/2 3*pi/4 pi])
//notice it's ".*", not "*"

>> plot (array)
//continuous plot

>> stem (array)
//discrete plot