机器学习 – octave

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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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