機械学習を1ヵ月で実践レベルにする #3 (Octave 編) ref: http://qiita.com/junichiro/items/33954f08411e33d33506

file0.txt

% octave-cli

file1.txt

>> ls
>> pwd
>> cd hoge

file2.txt

>> a = 1
a =  1
>> a = [1 2]
a =

   1   2

>> a = [1;2;3]
a =

   1
   2
   3

>> a = [1 2; 3 4]
a =

   1   2
   3   4

>> a = pi;
>> a
a =  3.1416

>> v = 1:0.3:2 % 初期値:ステップ数:終値
v =

    1.0000    1.3000    1.6000    1.9000

>> v = 1:6 % 初期値:(ステップ数1を省略):終値
v =

   1   2   3   4   5   6

>> ones(2,3)
ans =

   1   1   1
   1   1   1

>> zeros(3,2)
ans =

   0   0
   0   0
   0   0

>> 2*ones(2,3)
ans =

   2   2   2
   2   2   2

>> w = rand(2,3)
w =

   0.958006   0.225452   0.932911
   0.039494   0.743074   0.607472

>>  m = magic(3) % nxn の魔法陣を作る
m =

   8   1   6
   3   5   7
   4   9   2

>> eye(5)
ans =

Diagonal Matrix

   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

file3.txt

>> A = [1 2; 3 4; 5 6]
A =

   1   2
   3   4
   5   6

>> size(A)
ans =

   3   2

>> size(A, 1)
ans =  3
>> size(A, 2)
ans =  2
>> v = [1 2 3 4]
v =

   1   2   3   4

>> length(v)
ans =  4
>> A(1,:)
ans =

   1   2

>> A(2,:)
ans =

   3   4

>> A(:,1)
ans =

   1
   3
   5

>> A(:,2)
ans =

   2
   4
   6

>> A(:)
ans =

   1
   3
   5
   2
   4
   6

>> A(1:1)
ans =  1
>> A(1:2)
ans =

   1   3

>> A(1:3)
ans =

   1   3   5

>> A([1,3], :)
ans =

   1   2
   5   6

>> A(:,2) = [10;11;12]
A =

    1   10
    3   11
    5   12

>> A = [A, [100; 101; 102]]
A =

     1    10   100
     3    11   101
     5    12   102

>> A' % 転置
ans =

     1     3     5
    10    11    12
   100   101   102

file4.txt

>> who % 定義されている変数の一覧
Variables in the current scope:

A    a    ans  m    v    w

>> whos % 定義されている変数の一覧とそのサイズなど
Variables in the current scope:

   Attr Name        Size                     Bytes  Class
   ==== ====        ====                     =====  ===== 
        A           3x2                         48  double
        a           1x1                          8  double
        ans         3x1                         24  double
        m           3x3                         72  double
        v           1x4                         32  double
        w           2x3                         48  double

Total is 29 elements using 232 bytes