cvAdd(M1, M2, M3); //cvSub(M1, M2, M3); //cvMatMul(M1, M2, M3);

//CvMat* M1 = cvCreateMat(4,4,CV_32FC1);
  CvMat* M1 = cvCreateMat(4,4,CV_64FC1);
  cvSetIdentity(M1);//初始化矩阵为单位矩阵
  cvDoubleMatPrint(M1);

  CvMat* M2 = cvCreateMat(4,4,CV_64FC1);
  int i,j;

  printf("\n=====M2赋值为2.0==============\n");

   for(i=0;i<4;i++)
		 for(j=0;j<4;j++)
			 cvmSet(M2,i,j,2.0);
	CvMat* M3 = cvCreateMat(4,4,CV_64FC1);
	//cvAdd(M1, M2, M3);
	//cvSub(M1, M2, M3);
	cvMatMul(M1, M2, M3);

   for( i=0;i<4;i++)
   {
		 for( j=0;j<4;j++)
			 printf("%f ",cvmGet(M3,i,j));
		 printf("\n"); 
   }
  printf("\n===End:赋值为2.0==============\n");

 
  cvReleaseMat(&M1);
  cvReleaseMat(&M2);
  cvReleaseMat(&M3);