在octave中有很多的函数应用，例如：命令type magic查看magic函数的源码
1 magic is the user-defined function defined from: /usr/share/octave/6.4.0/m/special-matrix/magic.m
2
3 ########################################################################
4 ##
5 ## Copyright (C) 1999-2021 The Octave Project Developers
6 ##
7 ## See the file COPYRIGHT.md in the top-level directory of this
8 ## distribution or <https://octave.org/copyright/>.
9 ##
10 ## This file is part of Octave.
11 ##
12 ## Octave is free software: you can redistribute it and/or modify it
13 ## under the terms of the GNU General Public License as published by
14 ## the Free Software Foundation, either version 3 of the License, or
15 ## (at your option) any later version.
16 ##
17 ## Octave is distributed in the hope that it will be useful, but
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19 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 ## GNU General Public License for more details.
21 ##
22 ## You should have received a copy of the GNU General Public License
23 ## along with Octave; see the file COPYING. If not, see
24 ## <https://www.gnu.org/licenses/>.
25 ##
26 ########################################################################
27
28 ## -*- texinfo -*-
29 ## @deftypefn {} {} magic (@var{n})
30 ##
31 ## Create an @var{n}-by-@var{n} magic square.
32 ##
33 ## A magic square is an arrangement of the integers @code{1:n^2} such that the
34 ## row sums, column sums, and diagonal sums are all equal to the same value.
35 ##
36 ## Note: @var{n} must be a scalar greater than or equal to 3. If you supply
37 ## @var{n} less than 3, magic returns either a nonmagic square, or else the
38 ## degenerate magic squares 1 and [].
39 ## @end deftypefn
40
41 function A = magic (n)
42
43 if (nargin != 1)
44 print_usage ();
45 endif
46
47 n = fix (n);
48 if (n < 0)
49 error ("magic: N must be non-negative");
50 elseif (n < 1)
51 A = [];
52 elseif (mod (n, 2) == 1)
53
54 shift = floor ((0:n*n-1)/n);
55 c = mod ([1:n*n] - shift + (n-3)/2, n);
56 r = mod ([n*n:-1:1] + 2*shift, n);
57 A(c*n+r+1) = 1:n*n;
58 A = reshape (A, n, n);
59
60 elseif (mod (n, 4) == 0)
61
62 A = reshape (1:n*n, n, n)';
63 I = [1:4:n, 4:4:n];
64 J = fliplr (I);
65 A(I,I) = A(J,J);
66 I = [2:4:n, 3:4:n];
67 J = fliplr (I);
68 A(I,I) = A(J,J);
69
70 elseif (mod (n, 4) == 2)
71
72 m = n/2;
73 A = magic (m);
74 A = [A, A+2*m*m; A+3*m*m, A+m*m];
75 k = (m-1)/2;
76 if (k > 1)
77 I = 1:m;
78 J = [2:k, n-k+2:n];
79 A([I,I+m],J) = A([I+m,I],J);
80 endif
81 I = [1:k, k+2:m];
82 A([I,I+m],1) = A([I+m,I],1);
83 I = k + 1;
84 A([I,I+m],I) = A([I+m,I],I);
85
86 endif
87
88 endfunction
89
90
91 %!test
92 %! for i = 3:30
93 %! A = magic (i);
94 %! assert (norm(diff([sum(diag(A)),sum(diag(flipud(A))),sum(A),sum(A')])),0);
95 %! endfor
96
97 ## Not a magic square but we must return something (bug #46672).
98 ## While one day we may change the actual return of magic (2),
99 ## this properties still must be true.
100 %!test <*46672>
101 %! m = magic (2);
102 %! assert (size (m), [2 2]);
103 %! assert (m, [4 3; 1 2]);
104
105 %!assert (isempty (magic (0)))
106 %!assert (magic (1), 1)
107 %!assert (magic (1.5), 1)
108
109 ## Test input validation
110 %!error magic ()
111 %!error magic (1, 2)
112 %!error <N must be non-negative> magic (-5)
使用也特别容易，magic（3）
magic(3) ans = 8 1 6 3 5 7 4 9 2
查看帮助：
man magic
error: 'man' undefined near line 1, column 1
octave:9> help magic
warning: tempdir: '/tmp/' does not exist or is not a directory
warning: called from
tempdir at line 48 column 5
__makeinfo__ at line 135 column 17
help at line 109 column 24
'magic' is a function from the file /usr/share/octave/6.4.0/m/special-matrix/magic.m
-- magic (N)
Create an N-by-N magic square.
A magic square is an arrangement of the integers '1:n^2' such that
the row sums, column sums, and diagonal sums are all equal to the
same value.
Note: N must be a scalar greater than or equal to 3. If you supply
N less than 3, magic returns either a nonmagic square, or else the
degenerate magic squares 1 and [].
Additional help for built-in functions and operators is
available in the online version of the manual. Use the command
'doc <topic>' to search the manual index.
Help and information about Octave is also available on the WWW
at https://www.octave.org and via the [email protected]
mailing list.
通过系统函数magic的源码明显看出m函数有几个部分：
1、函数定义： function [返回变量列表(多个变量之间用逗号分割)] = 函数名称(言简意赅，顾名思义即可)(输入变量列表(多变量之间用逗号隔开))
2、帮助文本：第1行叫做H1行帮助文本，有特殊作用，经常用来说明函数的功能，版权等信息
3、函数主题：函数体语句段，%后边的是注释语句
4、函数最后的end语句，可以省略
说明：函数定义中function关键字、函数名称和参数列表的括号，其他都可以省略，其中函数名可以自己按照标识符的要求自己编写，其他都是不能乱改的。
对每一个函数，m环境自动生成两个变量nargin和nargout实现变量检测，无需声明可以直接使用
子函数一般位于主函数中，常常位于非第一个函数的位置，可以被主函数或其他子函数调用
主函数一般位于函数的第一个位置，函数名称于文件名称一般同名
1 %剔除向量a的奇异数据,系统的测量精度为可设置cal 2 function remainP = distriMethodV2(a, cal) 3 b = sort(a); %向量数据排序 xm = getXm(b); %获取向量的中位>值 fl = b(1:ceil(length(b)/2)); 4 if rem(length(b), 2) == 0 5 fl = [fl xm]; 6 end 7 fll = getXm(fl); 8 9 if rem(length(b), 2) ~= 0 10 fu = b(ceil(length(b)/2) : length(b)); 11 else 12 fu = [xm, b((length(b)/2 + 1) : length(b))]; 13 end 14 fuu = getXm(fu); 15 16 remainP = b(find(abs(b) <= cal*(fuu - fll))); 17 18 %求向量中位值 function xm = getXm(b) 19 if rem(length(b), 2) ~= 0 20 index = ceil(length(b)/2); 21 xm = b(index); 22 else 23 index = length(b)/2; 24 xm = (b(index) + b(index + 1))/2; 25 end
function mul = multiV2(a)
mul = 1;
for i = 1 : length(a)
mul = mul * a(i);
end
也可以：
function mul = multi(varargin)
mul = 1;
for i = 1 : length(varargin)
mul = mul * varargin{i};
end
标签：magic,函数,##,length,octave,mul From： https://www.cnblogs.com/guochaoxxl/p/17458171.html