//C++
 
#include "engine.h" //使用Matlab引擎需要包含的頭文件
#include <iostream>
using namespace std;
int main()
{
 Engine *m_engine; //創建Matlab引擎
 m_engine = NULL; //初始化引擎
 
 if((!m_engine && !(m_engine = engOpen(NULL)))) //打開引擎，此時會打開一個Matlab命令行窗口
 {
  return -1;
 }
 engSetVisible(m_engine,1); //將命令行窗口設為可見
 
 char buffer[255]; //記錄調試信息，方便調試
 engOutputBuffer(m_engine, buffer, 255); 
 
 
 double A[3][3] = {-1,1,0,
   -4,3,0,
    1,0,2}; 
 mxArray* AObj = mxCreateDoubleMatrix(3, 3, mxREAL); //創建Matlab的矩陣（大小3*3，實數）
 
 memcpy(mxGetPr(AObj), A, 3*sizeof(double)); //將C++的數據傳入Matlab中
 
 engPutVariable(m_engine, "A", AObj); //將AObj的值賦給A
 
  engEvalString(m_engine, "cd('E:\\MatlabScripts')"); //進入Matlab代碼的路徑 
 
  //調用Matlab中定義的函數“computeEigens”，文件名需與函數名一致，即“computeEigens.m”
  int k = 2;
 engEvalString(m_engine, "[eigVector,eigValue] = computeEigens(A, k);"); 
 
  //存儲計算結果
 engEvalString(m_engine,"save('E:\\eigVec_eigV.mat','eigVector','eigValue');");
 
 printf("%s", buffer);
 
 mxDestroyArray(AObj); //銷毀Matlab數組
 
 if (m_engine) //關閉Matlab引擎
 {
 engClose(m_engine);
 m_engine = NULL;
 }
 
 return 0;
 
}

%調用的Matlab代碼
%E:\MatlabScripts\computeEigens.m
 
function [ eigVector, eigValue ] = computeEigens( M, n_Eigens ) %n_Eigens為要求的特征值數量
 [EigenVectors,EigenValues] = eig(M);
 [sortedEigenValues, index] = sort(diag(EigenValues));
 eigValue = sortedEigenValues(1:n_Eigens);
 idx = index(1:n_Eigens);
 eigVector = EigenVectors(:,idx);
 
end