实验平台：ubuntu 12.04 + g++4.6 + matlab2012a
问题描述：
有一个c++程序main.cpp，和一个matlab函数myFunc.m。现在要做这件事：
1）从main.cpp中传递2个double类型的数值a和b到myFunc.m中
2）myFunc.m中求和（sum = a+b）
3）main.cpp中接收myFunc.m返回的和并输出。
思路：
1）设置matlab的编译器，使用gcc编译器。编译m文件成.so。
2）编译.cpp文件，编译时调用.so库（添加.so的路径到编译选项）。
步骤：
1）将自己的matlab函数（myFunc.m）编译成动态链接库
(1) 设定编译器为gcc，在matlab 命令行依次执行命令mex -setup和mbuild -setup：
>> mex -setup
Options files control which compiler to use, the compiler and link command options, and the runtime libraries to link against.
Using the 'mex -setup' command selects an options file that is
placed in ~/.matlab/R2012a and used by default for 'mex'. An options
file in the current working directory or specified on the command line
overrides the default options file in ~/.matlab/R2012a.
To override the default options file, use the 'mex -f' command
(see 'mex -help' for more information).
The options files available for mex are:
1: /opt/MATLAB/R2012a/bin/mexopts.sh :
Template Options file for building gcc MEX-files
0: Exit with no changes
Enter the number of the compiler (0-1):
1
/opt/MATLAB/R2012a/bin/mexopts.sh is being copied to ~/.matlab/R2012a/mexopts.sh
cp: cannot create regular file `~/.matlab/R2012a/mexopts.sh': Permission denied
**************************************************************************
Warning: The MATLAB C and Fortran API has changed to support MATLAB
variables with more than 2^32-1 elements. In the near future
you will be required to update your code to utilize the new
API. You can find more information about this at:
http://www.mathworks.com/help/techdoc/matlab_external/bsflnue-1.html
Building with the -largeArrayDims option enables the new API.
**************************************************************************
>> mbuild -setup
Options files control which compiler to use, the compiler and link command
options, and the runtime libraries to link against.
Using the 'mbuild -setup' command selects an options file that is
placed in ~/.matlab/R2012a and used by default for 'mbuild'. An options
file in the current working directory or specified on the command line
overrides the default options file in ~/.matlab/R2012a.
To override the default options file, use the 'mbuild -f' command (see 'mbuild -help' for more information).
The options files available for mbuild are:
1: /opt/MATLAB/R2012a/bin/mbuildopts.sh :
Build and link with MATLAB Compiler generated library via the system ANSI C/C++ compiler
0: Exit with no changes
Enter the number of the compiler (0-1):
1
/opt/MATLAB/R2012a/bin/mbuildopts.sh is being copied to ~/.matlab/R2012a/mbuildopts.sh
cp: cannot create regular file `~/.matlab/R2012a/mbuildopts.sh': Permission denied
>>
(2) 在matlab中，编写myFunc.m文件内容如下：
function [ C ] = myFunc(A, B)
C = A+B;
end
(3) 生成myFunc.m的动态链接库（.so）
>> mcc -W cpplib:libmyFunc -T link:lib myFunc.m -c
Warning: MATLAB Toolbox Path Cache is out of date and is not being used.
Type 'help toolbox_path_cache' for more info
>>
等待数秒，完成。可以看到myFunc.m所在的目录下生成了多个文件：
$ ls
libmyFunc.cpp libmyFunc.ctf libmyFunc.exports libmyFunc.h libmyFunc.so main.cpp mccExcludedFiles.log myFunc.m readme.txt
命令解释：其中-W是控制编译之后的封装格式；cpplib是指编译成C++的lib；cpplib冒号后面是指编译的库的名字；-T表示目标，link:lib表示要连接到一个库文件的目标，目标的名字即是.m函数的名字。-c表明需要生成.ctf文件，比如本例如果不加-c就不会生成“libmyFunc.ctf”。
生成的文件中打开“libmyFunc.h”可以看到一行：
extern LIB_libmyFunc_CPP_API void MW_CALL_CONV myFunc(int nargout, mwArray& C, const mwArray& A, const mwArray& B);
这个就是我们的myFunc.c函数待会儿在c++中调用时的接口。有4个参数，第一个是参数个数，第二个是用来接收函数返回值的，后面2个是从c++中传递进来的变量。我们还会用到“libmyFunc.h”中的另外2个函数：libmyFuncInitialize()初始化，和注销libmyFuncTerminate()。
2）编写main.cpp，代码如下：
#include <iostream>
#include "mclmcr.h"
#include "matrix.h"
#include "mclcppclass.h"
#include "libmyFunc.h"
#include "mclmcrrt.h"
using namespace std;
int main() {
// initialize lib，这里必须做初始化！
if( !libmyFuncInitialize())
{
std::cout << "Could not initialize libmyFunc!" << std::endl;
return -1;
}
// 用户输入2个数值
double a, b;
cout<<"Please input 2 numbers <a b> and then press enter: "<<endl;
cin >> a;
cin >> b;
double c; //used to receive the result
// 为变量分配内存空间, maltab只有一种变量，就是矩阵，为了和c++变量接轨，设置成1*1的矩阵
mwArray mwA(1, 1, mxDOUBLE_CLASS); //1,1表示矩阵的大小, mxDOUBLE_CLASS表示变量的精度
mwArray mwB(1, 1, mxDOUBLE_CLASS);
mwArray mwC(1, 1, mxDOUBLE_CLASS);
// 调用类里面的SetData函数给类赋值
mwA.SetData(&a, 1);
mwB.SetData(&b, 1);
// 调用自己的函数，求和。
myFunc(1, mwC, mwA, mwB);
c = mwC.Get(1, 1);
cout<<"The sum is: "<<c<<endl;
// 后面是一些终止调用的程序
// terminate the lib
libmyFuncTerminate();
// terminate MCR
mclTerminateApplication();
return EXIT_SUCCESS;
}
3）编译main.cpp函数，调用libmyFunc.so
$ g++ -o main -I. -I/opt/MATLAB/R2012a/extern/include -L. -L/opt/MATLAB/R2012a/runtime/glnxa64 main.cpp -lmyFunc -lm -lmwmclmcrrt -lmwmclmcr
开始编译时也遇到一些问题，主要是链接库路径问题导致的编译错误，详细错误汇总在另篇笔记里（ 点此查看）。
编译成功后，需要装一下MCR Installer，步骤点此。
运行结果：
$ ./main
Warning: latest version of matlab app-defaults file not found.
Contact your system administrator to have this file installed
Please input 2 numbers <a b> and then press enter:
10 100
The sum is: 110
$ ./main
Warning: latest version of matlab app-defaults file not found.
Contact your system administrator to have this file installed
Please input 2 numbers <a b> and then press enter:
1 1
The sum is: 2
源代码及编译过程中的所有文件已打包，点击这里可以下载。
参考：
http://www.oschina.net/question/565065_72598
http://blog.csdn.net/ylf13/article/details/20005347
http://developer.51cto.com/art/200909/150944.htm
http://www.cnblogs.com/xkfz007/archive/2012/02/02/2336298.html
http://www.cnblogs.com/tiandsp/archive/2013/02/26/2934070.html
http://blog.sciencenet.cn/blog-620659-579845.html
http://blog.csdn.net/nupt123456789/article/details/7463612
http://*.com/questions/3165080/how-to-call-matlab-from-c-code