日月为易，刚柔相推。 是故易有太极，是生两仪，两仪生四象，四象生八卦，八卦定吉凶，吉凶生大业。是故法象莫大乎天地，变通莫大乎四时，悬象著明莫大乎日月。
  本文目的一半是对《易经》卜卦知识的总结，另一半是对利用编程解决实际问题能力的锻炼。至于卜卦，玩玩而已，但是对于《易经》，里面有很多知识值得我们学习。

《易经》知识简介

  本来想重新理一下《易经》知识的，但是尝试一下之后发现三言两语解释不清楚，所以有兴趣的朋友可以读一下以前写的一篇文章。
  对于八卦（乾qián、坤kūn、震zhèn、巽xùn、坎kǎn、离lí、艮gèn、兑duì），可以用排列组合知识这样理解：，《易经》中阴阳的概念可对应二进制中的零和一；三位二进制可表示0_{7,分别对应这八个单卦；再由这八个单卦**摩荡**（即排列组合，这工作传说是周文王在狱中完成）而成六十四卦，即六个二进制位表示0}63，对应六十四卦。相传，图灵发明计算机的二进制概念，灵感就是来源于《易经》。这样也就解释了下面介绍的三钱筮法为什要摇六次。

三钱筮法简介

  三枚铜钱，作为钱筮用具。在焚香致敬祝祷命筮之后，将三枚钱币握于手中，左手在上象征“天”，右手在下象征“地”；随意在手中晃动，再抛掷于地，看三枚钱币的正反情况，确定卦爻的属性。
一个背，两个字，称作“单”．画作“ — ”为少阳。

两个背，一个字，称作“拆”，画作“ - - ”为少阴。

三个背，没有字，称作“重”，画作“ O ”为老阳，为阳爻，是变爻，主过去之事。

三个字，没有背，称作“交”，画作“ X ”为老阴，为阴爻，是变爻，主未来之事。

  共摇六次，第一次为初爻，画在卦的最下面，依次上升，第六次为第六爻，画在卦的最上边。如遇有X、O，再画出变卦来（由于能力以及对《易经》的了解有限，未能解决变卦的问题（多爻变动如何选择），即本文只考虑给出原始的本卦）。

卜卦程序设计

卜卦程序：三枚铜钱，共摇六次，依次输入字面朝上的次数。
第一步：先计算每次字面朝上次数所对应的阴阳爻（即二进制的零一表示）

function  [yy] = yao(n)
% 分析每爻的变化，输入铜钱摇得的字面数
%输出：yy表示阴阳爻，0为阴，1为阳
if n<0 || n>3
    error('The num your input is error,please input again ');
end 
switch n
    case 0             % 三背为重，老阳，阳爻，是变爻，主过去之事
        yy = 1; 
     case 1            %一字为拆，少阴
        yy = 0;
    case 2             %两字为单，少阳
        yy = 1;
    otherwise       %三字为交，老阴，阴爻，是变爻，主未来之事
        yy = 0;
end
end

第二步：由每三次摇得的阴阳爻，分别得出单卦

function  [gua] = gua(n1,n2,n3)
% 由三爻得一卦，输入每爻的阴阳
%输出八卦（后天八卦）：乾一、兑二、离三、震四、巽五、坎六、艮七、坤八
%阳爻时n为1，阴爻时n为0
gua = 1+(~n3) + (~n2)*2 +(~n1)*4;
end

第三步：由两个单卦组合，得出本卦

function name = duan_gua(in,out)
% 由起卦所得内外卦，输出全卦
%乾一、兑二、离三、震四、巽五、坎六、艮七、坤八
if  in<0  ||  in>8 || out<0 || out >8
    disp('The num  is error,please check it ');
    exit;
end 
gua_list = {
         '乾为天','天泽履','天火同人','天雷无妄','天风姤','天水讼','天山遁','天地否';
         '泽天夬','兑为泽','泽火革','泽雷随','泽风大过','泽水困','泽山咸','泽地萃';
         '火天大有','火泽睽','离为火','火雷噬嗑','火风鼎','火水未济','火山旅','火地晋';
         '雷天大壮','雷泽归妹','雷火丰','震为雷','雷风恒','雷水解','雷山小过','雷地豫';
         '风天小畜','风泽中孚','风火家人','风雷益','巽为风','风水涣','风山渐','风地观';
         '水天需','水泽节','水火既济','水雷屯','水风井','坎为水','水山蹇','水地比';
         '山天大畜','山泽损','山火贲','山雷颐','山风蛊','山水蒙','艮为山','山地剥';
         '地天泰','地泽临','地火明夷','地雷复','地风升','地水师','地山谦','坤为地';
         };
name = gua_list(in,out);
end

主程序：输入六次摇得的铜钱字面朝上数，依次调用各子函数，已经与GUI程序整合

%三钱筮法MATLAB实现
%起卦：三枚铜钱，共摇六次，依次输入字面朝上的次数。
function guaci = SuanGua(number)
c1 = yao(number(1));
c2 = yao(number(2));
c3 = yao(number(3));
c4 = yao(number(4));
c5 = yao(number(5));
c6 = yao(number(6));
guaci = duan_gua(gua(c1,c2,c3),gua(c4,c5,c6));

GUI界面设计

  图形界面设计使用操作流：在MATLAB的命令窗口中输入guide命令，打开guidequick start窗口，选择create new gui点ok，生成新的fig文件，然后再在窗口中进行各项操作。
有几点注意事项：
（1）图片的插入代码段：

function Changes_OpeningFcn(hObject, eventdata, handles, varargin)
handles.output = hObject;
 logo1 = importdata('taiji.jpg');              %**图片插入，句柄使用**
 set(handles.logo1, 'CDATA', logo1);
guidata(hObject, handles);

（2）callback （重要）：右击对象，在属性编辑器中修改相关参数(style,tag)，再在程序中对应位置修改相关代码段（查看回调函数），保证点击界面时程序执行逻辑顺序正确。
（3）系统的容错性：仔细考察程序所有可能出现的意外情况，并在程序中解决。比如：当在红色输入框中输入的不是1,2或3时，之前未修改时程序会闪退，修改之后会在红色输出框中显示“error”。

有兴趣的朋友如果想试试，可以将上面的三个函数和下面的GUI程序保存为m文件，并且将下图中的八卦logo截图保存为taiji.jpg（调整宽度：258，高度244）；将这五个文件保存在一个文件夹中，运行GUI程序即可；在红色输入框中依次输入六个数字（1~3,否则报错），点击‘开始断卦’，即可出现如下效果：

以下代码是在GUI设计窗口操作之后，matlab自动生成的，修改部分代码实现功能。为了保证程序的可读性，并未删除自动生成的大量注释和空行。

function varargout = Changes(varargin)
% CHANGES MATLAB code for Changes.fig
%      CHANGES, by itself, creates a new CHANGES or raises the existing
%      singleton*.
%
%      H = CHANGES returns the handle to a new CHANGES or the handle to
%      the existing singleton*.
%
%      CHANGES('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in CHANGES.M with the given input arguments.
%
%      CHANGES('Property','Value',...) creates a new CHANGES or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before Changes_OpeningFcn gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to Changes_OpeningFcn via varargin.
%
%      *See GUI Options on GUIDE's Tools menu.  Choose "GUI allows only one
%      instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help Changes

% Last Modified by GUIDE v2.5 25-Feb-2017 13:48:13

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @Changes_OpeningFcn, ...
                   'gui_OutputFcn',  @Changes_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
if nargin && ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
end

if nargout
    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
    gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT

% --- Executes just before Changes is made visible.
function Changes_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% varargin   command line arguments to Changes (see VARARGIN)

% Choose default command line output for Changes
handles.output = hObject;
 %logo1 = importdata('logo.jpg');
 %set(handles.logo, 'CDATA', logo);
 logo1 = importdata('taiji.jpg');                         %图片插入，使用句柄
 set(handles.logo1, 'CDATA', logo1);

% Update handles structure
guidata(hObject, handles);

% UIWAIT makes Changes wait for user response (see UIRESUME)
% uiwait(handles.figure1);

% --- Outputs from this function are returned to the command line.
function varargout = Changes_OutputFcn(hObject, eventdata, handles) 
% varargout  cell array for returning output args (see VARARGOUT);
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure
varargout{1} = handles.output;

% --- Executes when figure1 is resized.
function figure1_SizeChangedFcn(hObject, eventdata, handles)
% hObject    handle to figure1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

function edit1_Callback(hObject, eventdata, handles)
% hObject    handle to edit1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of edit1 as text
%        str2double(get(hObject,'String')) returns contents of edit1 as a double

% --- Executes during object creation, after setting all properties.
function edit1_CreateFcn(hObject, eventdata, handles)
% hObject    handle to edit1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

function edit2_Callback(hObject, eventdata, handles)
% hObject    handle to edit2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of edit2 as text
%        str2double(get(hObject,'String')) returns contents of edit2 as a double

% --- Executes during object creation, after setting all properties.
function edit2_CreateFcn(hObject, eventdata, handles)
% hObject    handle to edit2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

function edit3_Callback(hObject, eventdata, handles)
% hObject    handle to edit3 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of edit3 as text
%        str2double(get(hObject,'String')) returns contents of edit3 as a double

% --- Executes during object creation, after setting all properties.
function edit3_CreateFcn(hObject, eventdata, handles)
% hObject    handle to edit3 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

function edit4_Callback(hObject, eventdata, handles)
% hObject    handle to edit4 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of edit4 as text
%        str2double(get(hObject,'String')) returns contents of edit4 as a double


% --- Executes during object creation, after setting all properties.
function edit4_CreateFcn(hObject, eventdata, handles)
% hObject    handle to edit4 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

function edit5_Callback(hObject, eventdata, handles)
% hObject    handle to edit5 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of edit5 as text
%        str2double(get(hObject,'String')) returns contents of edit5 as a double


% --- Executes during object creation, after setting all properties.
function edit5_CreateFcn(hObject, eventdata, handles)
% hObject    handle to edit5 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

function edit6_Callback(hObject, eventdata, handles)
% hObject    handle to edit6 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of edit6 as text
%        str2double(get(hObject,'String')) returns contents of edit6 as a double

% --- Executes during object creation, after setting all properties.
function edit6_CreateFcn(hObject, eventdata, handles)
% hObject    handle to edit6 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

function edit7_Callback(hObject, eventdata, handles)
% hObject    handle to edit7 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of edit7 as text
%        str2double(get(hObject,'String')) returns contents of edit7 as a double

% --- Executes during object creation, after setting all properties.
function edit7_CreateFcn(hObject, eventdata, handles)
% hObject    handle to edit7 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
n1 = get(handles.edit1,'string');          %**开始断卦对应的回调函数**  
n1 = str2num(n1);
n2 = get(handles.edit2,'string');                      %输入 
n2 = str2num(n2);
n3 = get(handles.edit3,'string');
n3 = str2num(n3);
n4 = get(handles.edit4,'string');
n4 = str2num(n4);
n5 = get(handles.edit5,'string');
n5 = str2num(n5);
n6 = get(handles.edit6,'string');
n6 = str2num(n6);
number = [n1,n2,n3,n4,n5,n6];

if length(number)~=6
    set(handles.edit7,'string','error');
else
    guaci = SuanGua(number);                          %算卦程序处理
    set(handles.edit7,'string',guaci);                %输出
end

% --- Executes on button press in pushbutton2.
function pushbutton2_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
close(Changes);

% --- If Enable == 'on', executes on mouse press in 5 pixel border.
% --- Otherwise, executes on mouse press in 5 pixel border or over text5.
function text5_ButtonDownFcn(hObject, eventdata, handles)
% hObject    handle to text5 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)


% --- Executes on button press in logo.
function logo_Callback(hObject, eventdata, handles)
% hObject    handle to logo (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% --- Executes on button press in logo1.
function logo1_Callback(hObject, eventdata, handles)
% hObject    handle to logo1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

function edit11_Callback(hObject, eventdata, handles)
% hObject    handle to edit11 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of edit11 as text
%        str2double(get(hObject,'String')) returns contents of edit11 as a double

% --- Executes during object creation, after setting all properties.
function edit11_CreateFcn(hObject, eventdata, handles)
% hObject    handle to edit11 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end