C++调用Opencv实现基本矩阵操作
1、生成常用矩阵
Mat类中的函数eye(),one()在mat.hpp文件中有申明：
/*@param rows Number of rows.
@param cols Number of columns.
@param type Created matrix type.*/
static MatExpr eye(int rows, int cols, int type);
static MatExpr ones(int rows, int cols, int type);
/*@param size Alternative matrix size specification as Size(cols, rows) .
@param type Created matrix type.*/
static MatExpr eye(Size size, int type);
static MatExpr ones(Size size, int type);
/*@param ndims Array dimensionality.
@param sz Array of integers specifying the array shape.
@param type Created matrix type.*/
static MatExpr ones(int ndims, const int* sz, int type);
生成矩阵：
#include
#include
using namespace std;
using namespace cv;
int main()
{
Mat m1 = Mat::eye(4, 4, CV_32F);
Mat m2 = Mat::eye(Size(5, 5), CV_32S);
Mat m3 = Mat::ones(3, 4, CV_32F);
Mat m4 = (Mat_ < float >(3, 3) << 1, 2, 3, 4, 5, 6, 7, 8, 9);
cout << "m1="</*@param d index of the diagonal, with the following values:
- `d=0` is the main diagonal.
- `d<0` is a diagonal from the lower half. For example, d=-1 means the diagonal is set
immediately below the main one.
- `d>0` is a diagonal from the upper half. For example, d=1 means the diagonal is set
immediately above the main one.*/
Mat diag(int d=0) const;
/* @brief creates a diagonal matrix
The method creates a square diagonal matrix from specified main diagonal.
@param d One-dimensional matrix that represents the main diagonal.*/
static Mat diag(const Mat& d); 代码调用实现：
#include
#include
using namespace std;
using namespace cv;
int main()
{
Mat m4 = (Mat_ < float >(3, 3) << 1, 2, 3, 4, 5, 6, 7, 8, 9);
Mat m5= (Mat_ < float >(4, 1) << 1, 2, 3, 4);
Mat m40=m4.diag(0);//提取主对角
Mat m41=m4.diag(1);
Mat m42=m4.diag(-1);
Mat diag_m5 = Mat::diag(m5);//生成对角矩阵
cout <<"m4=\n"<< m4<<"\nm40=\n"<< m40<<"\nm41=\n" << m41<<"\nm42=\n" << m42 < 输出为： 
3、利用Opencv实现Matlab的点乘和点
实现2个矩阵元素与元素
/*Example:
@code
Mat C = A.mul(5/B); // equivalent to divide(A, B, C, 5)
@endcode
@param m Another array of the same type and the same size as \*this, or a matrix
expression.
@param scale Optional scale factor.*/
MatExpr mul(InputArray m, double scale=1) const;之前的相乘或相除,其输出结果如下：
Mat m1 = (Mat_ < float >(3, 3) << 1, 2, 3, 4, 5, 6, 7, 8, 9);
Mat m2 = (Mat_ < float >(3, 3) << 1, 2, 3, 4, 5, 6, 7, 8, 9);
cout<<"m1=\n"< 
4、求矩阵的二范数（矩阵与矩阵之间，矩阵自己）
/*@param src1 first input array.
@param normType type of the norm (see #NormTypes).
@param mask optional operation mask; it must have the same size as src1 and CV_8UC1 type.*/
double norm(InputArray src1, int normType = NORM_L2, InputArray mask = noArray());
/*@param src1 first input array.
@param src2 second input array of the same size and the same type as src1.
@param normType type of the norm (see #NormTypes).
@param mask optional operation mask; it must have the same size as src1 and CV_8UC1 type*/
double norm(InputArray src1, InputArray src2,int normType = NORM_L2, InputArray mask = noArray());API函数无src2的时候的公式是 ：
另外一个有src2的时候的公式是：
double result = 0.0,result2=0.0;
Mat m1 = (Mat_ < float >(3, 3) << 1, 2, 3, 4, 5, 6, 7, 8, 9);
Mat m2 = Mat::ones(3,3,CV_32F);
Mat m3 = 3 * m2;
result = cv::norm(m1, NORM_L2);
result2 = cv::norm(m3,m2,NORM_L2);
cout <<"result="<< result << endl;
cout << "result2=" << result2 << endl;
getchar();输出的结果为：result=16.8819，result2=6