octave机器学习利器:
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>> 5+6
ans = 11
>> 3-2
ans = 1
>> 5*8
ans = 40
>> 1/2
ans = 0.50000
>> 2^6
ans = 64
>> 1 == 2 %false
ans = 0
>> 1 ~= 2 %true
ans = 1
>> 8>1 && 0 %AND
ans = 0
>> 9>1 || 1 %OR
ans = 1
>> xor(1,0)
ans = 1
>> PS1('>>>');
>>>
>>>a = 3
a = 3
>>>a = 3; #分号抑制打印
>>>
>>>a = 3.14;
>>>a
a = 3.1400
>>>disp(a);
3.1400
>>>disp(sprintf('2 decimals: %0.2f', a));
decimals: 3.14
>>>a=pi
a = 3.1416
>>>format long
>>>a
a = 3.14159265358979
>>>format short
>>>a
a = 3.1416
>>>A = [1 2; 3 4; 5 6]
A =
2
4
6
>>>a = [1 2;
4;
6]
a =
2
4
6
>>>v = [1 2 3]
v =
2 3
>>>v = [1; 2; 3]
v =
2
>>>v = 1:0.1:2
v =
Columns 1 through 4:
1.0000 1.1000 1.2000 1.3000
Columns 5 through 8:
1.4000 1.5000 1.6000 1.7000
Columns 9 through 11:
1.8000 1.9000 2.0000
>>>v = 1:6
v =
1 2 3 4 5 6
>>>ones(2,3)
ans =
1 1
1 1
>>>w = ones(1,3)
w =
1 1
>>>w = rand(3,3)
w =
0.91025 0.82671 0.14067
0.90400 0.34350 0.51289
0.25501 0.24975 0.80750
// 高斯分布 (正态分布)
>>>w = randn(1,3)
w =
-0.052546 -1.786869 0.754202
w = -6 + sqrt(10)*(randn(1,10000));
hist(w)
hist(w, 50)
>> eye(4)
ans =
Diagonal Matrix
0 0 0
1 0 0
0 1 0
0 0 1
>> help
For help with individual commands and functions type
help NAME
(replace NAME with the name of the command or function you would
like to learn more about).
For a more detailed introduction to GNU Octave, please consult the
manual. To read the manual from the prompt type
doc
GNU Octave is supported and developed by its user community.
For more information visit http://www.octave.org.
>> A = [1 2; 3 4; 5 6]
A =
2
4
6
>> size(A)
ans =
2
>> sz = size(A)
sz =
2
>> size(sz)
ans =
2
>> size(A,1)
ans = 3
>> size(A,2)
ans = 2
>> V = [1 2 3 4]
V =
2 3 4
>> length(V)
ans = 4
>> length(A)
ans = 3
>> pwd
ans = C:\Users\xin
>> cd 'E:\TEMPsrc\octave'
>> pwd
ans = E:\TEMPsrc\octave
>> ls
>> load featuresX.dat
>> load priceY.dat
>> load('featuresX.dat')
>> who
Variables in the current scope:
a ans b c
>> whos
Variables in the current scope:
Attr Name Size Bytes Class
==== ==== ==== ===== =====
a 1x1 8 doubl
e
ans 1x17 17 char
b 1x1 8 doubl
e
c 1x1 8 doubl
e
d 3x2 48 doubl
e
Total is 26 elements using 89 bytes
>> who
Variables in the current scope:
a ans b c d
>> clear a
>> who
Variables in the current scope:
ans b c d
>> save hello.mat d
>> clear
>> who
>> v = [1 2; 3 4; 5 6; 7 8; 9 0]
v =
2
4
6
8
0
< -ascii %save as text(ASCII)
>> A = [1 2; 3 4; 5 6]
A =
2
4
6
>> A(3,2)
ans = 6
>> A(2,:)
ans =
4
>> A(:,2)
ans =
4
>> A([1 3], 🙂
ans =
1 2
5 6
>> A(:,2) = [10;11;12]
A =
10
11
12
>> A = [A, [100;101;102]]
A =
10 100
11 101
12 102
>> A(:)
ans =
3
10
12
101
>> A = [1 2; 3 4; 5 6];
>> B = [11 12; 13 14; 15 16];
>> C = [A B]
C =
2 11 12
4 13 14
6 15 16
>> C = [A; B]
C =
2
4
6
12
14
16
>> A = [1 2; 3 4; 5 6];
>> B = [11 12; 13 14; 15 16];
>> C = [1 1; 2 2];
>> A*C
ans =
5
11
17
>> A .* B
ans =
24
56
96
>> A .^ 2
ans =
4
16
36
>> V = [1; 2; 3];
>> 1 ./ V
ans =
1.00000
0.50000
0.33333
>> 1 ./ A
ans =
1.00000 0.50000
0.33333 0.25000
0.20000 0.16667
>> log(V)
ans =
0.00000
0.69315
1.09861
>> exp(V)
ans =
2.7183
7.3891
20.0855
>> abs(V)
ans =
2
>> v = [1;2;3]
v =
2
>> v + ones(length(v), 1)
ans =
3
>> v + ones(3,1)
ans =
3
>> v + 1
ans =
3
>> A
A =
2
4
6
>> A'
ans =
3 5
4 6
>> a = [1 15 2 0.5]
a =
1.00000 15.00000 2.00000 0.50000
>> val = max(a)
val = 15
>> [val, ind] = max(a)
val = 15
ind = 2
a =
1.00000 15.00000 2.00000 0.50000
>> a < 3
ans =
0 1 1
>> find(a < 3)
ans =
3 4
>> A = magic(3)
A =
1 6
5 7
9 2
>> [r, c] = find(A >= 7)
r =
3
c =
2
>> a
a =
1.00000 15.00000 2.00000 0.50000
>> sum(a)
ans = 18.500
>> prod(a)
ans = 15
>> floor(a)
ans =
15 2 0
>> ceil(a)
ans =
15 2 1
>> max(rand(3), rand(3))
ans =
0.957477 0.083887 0.459507
0.799441 0.975439 0.927632
0.888604 0.942436 0.612661
>> A
A =
1 6
5 7
9 2
>> max(A, [], 1)
ans =
9 7
>> max(max(A))
ans = 9
>> max(A(:))
ans = 9
>> A = magic(5)
A =
24 1 8 15
5 7 14 16
6 13 20 22
12 19 21 3
18 25 2 9
>> sum(A,1)
ans =
65 65 65 65
>> sum(A,2)
ans =
65
65
>> sum(sum(A.*eye(5)))
ans = 65
>> eye(9)
ans =
Diagonal Matrix
0 0 0 0 0 0 0 0
1 0 0 0 0 0 0 0
0 1 0 0 0 0 0 0
0 0 1 0 0 0 0 0
0 0 0 1 0 0 0 0
0 0 0 0 1 0 0 0
0 0 0 0 0 1 0 0
0 0 0 0 0 0 1 0
0 0 0 0 0 0 0 1
>> flipud(eye(9))
ans =
Permutation Matrix
0 0 0 0 0 0 0 1
0 0 0 0 0 0 1 0
0 0 0 0 0 1 0 0
0 0 0 0 1 0 0 0
0 0 0 1 0 0 0 0
0 0 1 0 0 0 0 0
0 1 0 0 0 0 0 0
1 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
>> A = magic(3)
A =
1 6
5 7
9 2
>> pinv(A)
ans =
0.147222 -0.144444 0.063889
-0.061111 0.022222 0.105556
-0.019444 0.188889 -0.102778
>> temp = pinv(A)
temp =
0.147222 -0.144444 0.063889
-0.061111 0.022222 0.105556
-0.019444 0.188889 -0.102778
>> temp * A
ans =
1.00000 0.00000 -0.00000
-0.00000 1.00000 0.00000
0.00000 0.00000 1.00000
>> t=[0:0.01:0.98];
>> y1 = sin(2*pi*4*t);
>> plot(t,y1);
>> t=[0:0.01:0.98];
>> y2 = cos(2*pi*4*t);
>> plot(t,y2);
>> plot(t, y1);
>> hold on;
>> plot(t, y2, 'r');
>> xlabel('time')
>> ylabel('value')
>> legend('sin', 'cos')
>> title('my plot')
>> print -dpng 'myplot.png'
>> close
>> figure(1); plot(t, y1);
>> figure(2); plot(t, y2);
>> subplot(1,2,1);
>> plot(t, y1);
>> subplot(1,2,2);
>> plot(t, y2);
>> axis([0.5 1 -1 1])
>> clf;
>> A = magic(5);
>> imagesc(A)
>> imagesc(A), colorbar, colormap gray;
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