[TOC]
Octabe install
推荐 使用Octave安装包安装.
On Ubuntu, you can use:
sudo apt-get update && sudo apt-get install octave
On Fedora, you can use:
sudo yum install octave-forge
Octave 使用
GNU Octave, version 4.2.2
Copyright (C) 2018 John W. Eaton and others.
Octave was configured for "x86_64-pc-linux-gnu".
...
For more information, visit http://www.octave.org/get-involved.html
>> 1 ==2
ans = 0
>> 1~=2
ans = 1
# 9x9 随机 0~1
>> rand(9,9)
ans =
0.3560386 0.4607871 0.8059847 0.2042094 0.2411058 0.9311803 0.8023873 0.8208079 0.9631931
0.4604231 0.0222901 0.6693275 0.5887816 0.0076518 0.1670580 0.6335819 0.1711659 0.1405882
0.0519485 0.3400714 0.2909762 0.3687556 0.7300303 0.3436051 0.1679526 0.2550348 0.0342722
0.9379501 0.7760394 0.0859048 0.3292712 0.2385854 0.8567406 0.2433711 0.8027390 0.4103872
0.8297066 0.5138018 0.3540072 0.7688630 0.7550758 0.0676738 0.3528168 0.5365513 0.8800598
0.3350162 0.8376844 0.7863446 0.6448189 0.1355422 0.0235755 0.2975952 0.2879286 0.8854084
0.2484960 0.2086548 0.4821656 0.5838678 0.2676164 0.8016253 0.5552146 0.2787187 0.7647289
0.7559019 0.2639478 0.4199944 0.5312557 0.5202589 0.7852354 0.5681352 0.1088001 0.6572705
0.9477478 0.4998028 0.4179308 0.0513819 0.8775790 0.5860457 0.3993368 0.3765168 0.2140254
>> ones(9,9)
ans =
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1
>> W = zeros(9,9);
>> W
W =
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
>> rand(1, 2)
ans =
0.76409 0.77792
>> sqrt(9)
ans = 3
>> A = rand(1, 100000);
>> hist(A, 20)
# 符合正太分布的随机数，randn， u=0，seigema=1
>> A = randn (1,10000);
>> hist(A, 50)
# u= -10 ， segema = 98
>> W = -10 + sqrt(98)*(randn(1,10000));
>> hist(W)
>> hist(W, 50)
>> eye(5)
ans =
Diagonal Matrix #单位矩阵
1 0 0 0 0
0 1 0 0 0
0 0 1 0 0
0 0 0 1 0
0 0 0 0 1
>> size (W)
ans =
1 10000
>> length (W)
ans = 10000
>> W = zeros (5)
W =
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
>> length (W)
ans = 5
>> W = zeros (5, 4)
W =
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
>> length (W)
ans = 5
>> W = zeros (2, 4)
W =
0 0 0 0
0 0 0 0
>> length (W)
ans = 4
# 注意，length 表示 航和列中，较大的这个
# length (W) = max (size (A))
octave还可以执行部分shell命令
>> pwd
ans = /home/alex/data_files/software/xmind/xmind-8-update8-linux/XMind_amd64
>> cd
>> pwd
ans = /home/alex
>> ls
2018-10-16 18-01-44
>> load sogou-qimpanel:0.pid
>> who
Variables in the current scope:
W ans
举证其他表示方法
>> A = [1 2; 3 4; 5 6]
A =
1 2
3 4
5 6
>> B = [11 12; 13 14; 15 16]
B =
11 12
13 14
15 16
>> C = [A B]
C =
1 2 11 12
3 4 13 14
5 6 15 16
>> D = [A; B]
D =
1 2
3 4
5 6
11 12
13 14
15 16
# transpose
>> D'
ans =
1 3 5 11 13 15
2 4 6 12 14 16
>> E = rand(5)
E =
0.382889 0.826820 0.143657 0.105050 0.799284
0.342433 0.729053 0.571096 0.498017 0.581522
0.299401 0.346902 0.273341 0.138887 0.505162
0.745145 0.132160 0.319004 0.978364 0.488847
0.368702 0.029850 0.391279 0.496332 0.533725
>> E = rand(5,1)
E =
0.99898
0.63184
0.95289
0.37744
0.91223
最大值
>> E = rand(1,10)
E =
0.790997 0.471432 0.598649 0.593467 0.342134 0.960598 0.752763 0.021469 0.271880 0.111108
>> max (E)
ans = 0.96060
>> [value, index] = max(E)
value = 0.96060
index = 6
过滤筛选
>> E < 0.5
ans =
0 1 0 0 1 0 0 1 1 1
>> find(E < 0.5)
ans =
2 5 8 9 10
>> E
E =
0.790997 0.471432 0.598649 0.593467 0.342134 0.960598 0.752763 0.021469 0.271880 0.111108
>> [value, index] = find(E<0.5)
value =
1 1 1 1 1
index =
2 5 8 9 10
>> E = rand(5,5)
E =
0.787163 0.617232 0.703976 0.436314 0.410497
0.440223 0.812849 0.242780 0.869555 0.278506
0.240996 0.931844 0.060643 0.612793 0.227300
0.451394 0.673056 0.184734 0.143215 0.803382
0.795615 0.979938 0.857430 0.963706 0.765059
>> [value, index] = find(E<0.5)
value =
2
3
4
2
3
4
1
4
1
2
3
index =
1
1
1
3
3
3
4
4
5
5
5
>> [rows, colums] = find(E<0.5)
rows =
2
3
4
2
3
4
1
4
1
2
3
colums =
1
1
1
3
3
3
4
4
5
5
5
相关计算
>> sum(E)
ans =
2.9953 2.4057 2.3705 3.2331 2.2077
>> prod(E)
ans =
0.0337328 0.0098164 0.0058173 0.0925647 0.0138977
>> floor (E)
ans =
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
>> ceil (E)
ans =
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
>> F = randn (5)
F =
1.73542 -0.97333 0.90465 0.28529 1.89615
-0.56606 -0.78233 -1.20289 0.77386 0.64770
-1.54203 0.49252 1.34071 1.56246 -1.48515
-1.82310 -1.68507 1.41672 -1.24164 -0.20081
1.12516 0.63253 -1.90412 -1.23104 0.66748
>> ceil (F)
ans =
2 -0 1 1 2
-0 -0 -1 1 1
-1 1 2 2 -1
-1 -1 2 -1 -0
2 1 -1 -1 1
>> floor (F)
ans =
1 -1 0 0 1
-1 -1 -2 0 0
-2 0 1 1 -2
-2 -2 1 -2 -1
1 0 -2 -2 0
>> prod(F)
ans =
-3.10731 -0.39973 3.93571 0.52725 0.24448
>> sum(F)
ans =
-1.07060 -2.31567 0.55507 0.14892 1.52537
>> G1 = rand(3)
G1 =
0.536005 0.039219 0.756845
0.378762 0.097467 0.124591
0.567407 0.395335 0.371280
>> G2 = rand(3)
G2 =
0.210937 0.263702 0.241626
0.191786 0.871084 0.903337
0.350747 0.768891 0.047243
>> max(G1,G2)
ans =
0.53601 0.26370 0.75684
0.37876 0.87108 0.90334
0.56741 0.76889 0.37128
>> max(G1)
ans =
0.56741 0.39533 0.75684
>> max(G1, [], 1)
ans =
0.56741 0.39533 0.75684
>> max(G1, [], 2)
ans =
0.75684
0.37876
0.56741
>> max(max(G1))
ans = 0.75684
>> max(G1(:))
ans = 0.75684
>> G1(:)
ans =
0.536005
0.378762
0.567407
0.039219
0.097467
0.395335
0.756845
0.124591
0.371280
>> A
A =
1 2
3 4
5 6
magic使用
>> magic (9)
ans =
47 58 69 80 1 12 23 34 45
57 68 79 9 11 22 33 44 46
67 78 8 10 21 32 43 54 56
77 7 18 20 31 42 53 55 66
6 17 19 30 41 52 63 65 76
16 27 29 40 51 62 64 75 5
26 28 39 50 61 72 74 4 15
36 38 49 60 71 73 3 14 25
37 48 59 70 81 2 13 24 35
>> eye (9)
ans =
Diagonal Matrix
1 0 0 0 0 0 0 0 0
0 1 0 0 0 0 0 0 0
0 0 1 0 0 0 0 0 0
0 0 0 1 0 0 0 0 0
0 0 0 0 1 0 0 0 0
0 0 0 0 0 1 0 0 0
0 0 0 0 0 0 1 0 0
0 0 0 0 0 0 0 1 0
0 0 0 0 0 0 0 0 1
>> magic (9) .* eye (9)
ans =
47 0 0 0 0 0 0 0 0
0 68 0 0 0 0 0 0 0
0 0 8 0 0 0 0 0 0
0 0 0 20 0 0 0 0 0
0 0 0 0 41 0 0 0 0
0 0 0 0 0 62 0 0 0
0 0 0 0 0 0 74 0 0
0 0 0 0 0 0 0 14 0
0 0 0 0 0 0 0 0 35
>> sum(sum(magic (9) .* eye(9)))
ans = 369
>> sum(magic (9) .* eye(9))
ans =
47 68 8 20 41 62 74 14 35
逆矩阵和转置
inverse and transport
# θ = ( X^T X )^−1 X^T y
# theta = pinv(X'*X)*X'*y
# inv pinv, pinv 可以处理逆矩阵不是线性相关的问题。
>> A
A =
30 39 48 1 10 19 28
38 47 7 9 18 27 29
46 6 8 17 26 35 37
5 14 16 25 34 36 45
13 15 24 33 42 44 4
21 23 32 41 43 3 12
22 31 40 49 2 11 20
>> pinv(A)
ans =
8.1633e-04 8.1633e-04 2.1165e-02 -1.9533e-02 -2.0907e-03 4.1386e-03 4.0104e-04
-2.0907e-03 2.4072e-02 -1.9533e-02 1.2316e-03 4.0104e-04 8.1633e-04 8.1633e-04
2.1165e-02 -1.9117e-02 4.0104e-04 -2.0907e-03 3.7233e-03 8.1633e-04 8.1633e-04
-1.7041e-02 8.1633e-04 8.1633e-04 8.1633e-04 8.1633e-04 8.1633e-04 1.8673e-02
8.1633e-04 8.1633e-04 -2.0907e-03 3.7233e-03 1.2316e-03 2.0750e-02 -1.9533e-02
8.1633e-04 8.1633e-04 1.2316e-03 4.0104e-04 2.1165e-02 -2.2439e-02 3.7233e-03
1.2316e-03 -2.5059e-03 3.7233e-03 2.1165e-02 -1.9533e-02 8.1633e-04 8.1633e-04
>> A * pinv(A)
ans =
1.0000e+00 -4.5103e-17 -1.5266e-16 -1.0408e-15 -4.4409e-16 5.5338e-16 7.6675e-16
-7.0907e-16 1.0000e+00 4.7878e-16 2.4633e-16 2.4980e-16 4.2067e-17 -7.4853e-16
7.4463e-16 -1.4485e-16 1.0000e+00 -8.9165e-16 2.4980e-16 1.1493e-16 4.3455e-16
-3.3437e-16 5.2822e-16 -4.3715e-16 1.0000e+00 2.7756e-17 1.6697e-16 -6.5052e-17
-1.2317e-16 2.1684e-16 -1.8908e-16 -5.9674e-16 1.0000e+00 2.5847e-16 9.9053e-16
-6.6787e-16 -3.0878e-16 1.0270e-15 6.9389e-17 -2.7756e-17 1.0000e+00 -5.2042e-16
-5.9501e-16 1.0408e-17 4.8572e-16 -1.3878e-17 3.3307e-16 -1.9082e-17 1.0000e+00
画图
>> t=[0:0.01:0.98];
>> y1=sin(2*pi*4*t);
>> plot(t,y1);
>> y2=cos(2*pi*4*t);
>> plot(t,y2)
一个图，多个曲线
>> t=[0:0.01:0.98];
>> y1=sin(2*pi*4*t);
>> y2=cos(2*pi*4*t);
>> hold on; #保持上图
>> plot(t,y1);
>> plot(t,y2)
>> xlabel ('time')
>> ylabel ('value')
# 图例线
>> legend('sin', 'cos')
>> title('my plot')
# 导出
>> cd
>> print -dpng 'myplot.png'
多个figure同时呈现
>> t=[0:0.01:0.98];
>> y1=sin(2*pi*4*t);
>> y2=cos(2*pi*4*t);
>> hold on;
>> figure (1);plot(t,y1);
>> figure (2);plot(t,y2);
子图显示
>> subplot (1,2,1);
>> plot(t,y1);
>> subplot (1,2,2);
>> plot(t,y2);
imagesc
>> imagesc (magic (5))
>> imagesc (magic (15)), colorbar, colormap gray;
>> help imagesc
'imagesc' is a function from the file /usr/share/octave/4.2.2/m/image/imagesc.m
-- imagesc (IMG)
-- imagesc (X, Y, IMG)
-- imagesc (..., CLIMITS)
-- imagesc (..., "PROP", VAL, ...)
-- imagesc ("PROP1", VAL1, ...)
-- imagesc (HAX, ...)
-- H = imagesc (...)
Display a scaled version of the matrix IMG as a color image.
>> for i=1:10, v(i)=2^i; end;
>> v
v =
2 4 8 16 32 64 128 256 512 1024
>> include=1:10;
>> for i=include , disp(i); end;
1
2
3
4
5
6
7
8
9
10
>> i=1; while i<=5. v(i) = 100; i=i+1; end
>> v
v =
100 100 100 100 100 64 128 256 512 1024
>> while true,
v(i) = 999;
if i ==7, break;
end; end;
>> v
v =
100 100 100 100 100 999 999 256 512 1024
>> i = 1;
>> while true,
v(i) = 999;
i = i+ 1;
if i ==7, break;
end; end;
>> v
v =
999 999 999 999 999 999 999 256 512 1024
>> x = 2; if x ==1 , disp('the value is one');
elseif x == 2, disp('the value is two');
else disp('the value is not one or two');
end;
好啦，有这些基础就够用啦。再加上有help的帮助，遇到上面问题就知道怎么找解决办法了。