#include <opencv2/opencv.hpp>

using namespace std;
using namespace cv;

int main( int argc, char** argv )
{
        Mat src = Mat(Size(320,240),CV_64F);;
        namedWindow("test");

        cout << "press any key to close" << endl;

        while(true){
                randn(src,0,1.0);
                imshow("test",src);
                if(waitKey() > 0) break;
        }
}

g++ cv.cpp -I"/usr/local/Cellar/opencv/3.4.1_5/include" -L"/usr/local/Cellar/opencv/3.4.1_5/lib/" -lopencv_core -lopencv_highgui -o cv

g++ cv.cpp -I"/usr/local/Cellar/opencv/3.4.1_5/include" -L"/usr/local/Cellar/opencv/3.4.1_5/lib/" -lopencv_core -lopencv_highgui -o cv

Undefined symbols for architecture x86_64:
  "cv::drawMatches(cv::_InputArray const&, std::__1::vector<cv::KeyPoint, std::__1::allocator<cv::KeyPoint> > const&, cv::_InputArray const&, std::__1::vector<cv::KeyPoint, std::__1::allocator<cv::KeyPoint> > const&, std::__1::vector<cv::DMatch, std::__1::allocator<cv::DMatch> > const&, cv::_InputOutputArray const&, cv::Scalar_<double> const&, cv::Scalar_<double> const&, std::__1::vector<char, std::__1::allocator<char> > const&, int)", referenced from:
      _main in cv-c462f9.o
  "cv::xfeatures2d::SURF::create(double, int, int, bool, bool)", referenced from:
      _main in cv-c462f9.o
  "cv::findHomography(cv::_InputArray const&, cv::_InputArray const&, int, double, cv::_OutputArray const&, int, double)", referenced from:
      _main in cv-c462f9.o
  "cv::DescriptorMatcher::DescriptorCollection::~DescriptorCollection()", referenced from:
      cv::FlannBasedMatcher::~FlannBasedMatcher() in cv-c462f9.o
  "cv::DescriptorMatcher::~DescriptorMatcher()", referenced from:
      cv::FlannBasedMatcher::~FlannBasedMatcher() in cv-c462f9.o
  "cv::FlannBasedMatcher::FlannBasedMatcher(cv::Ptr<cv::flann::IndexParams> const&, cv::Ptr<cv::flann::SearchParams> const&)", referenced from:
      _main in cv-c462f9.o
  "cv::line(cv::_InputOutputArray const&, cv::Point_<int>, cv::Point_<int>, cv::Scalar_<double> const&, int, int, int)", referenced from:
      _main in cv-c462f9.o
  "cv::flann::IndexParams::~IndexParams()", referenced from:
      cv::flann::KDTreeIndexParams::~KDTreeIndexParams() in cv-c462f9.o
      cv::flann::SearchParams::~SearchParams() in cv-c462f9.o
  "cv::flann::SearchParams::SearchParams(int, float, bool)", referenced from:
      cv::Ptr<cv::flann::SearchParams> cv::makePtr<cv::flann::SearchParams>() in cv-c462f9.o
  "cv::flann::KDTreeIndexParams::KDTreeIndexParams(int)", referenced from:
      cv::Ptr<cv::flann::KDTreeIndexParams> cv::makePtr<cv::flann::KDTreeIndexParams>() in cv-c462f9.o
  "cv::imread(cv::String const&, int)", referenced from:
      _main in cv-c462f9.o
  "cv::DescriptorMatcher::match(cv::_InputArray const&, cv::_InputArray const&, std::__1::vector<cv::DMatch, std::__1::allocator<cv::DMatch> >&, cv::_InputArray const&) const", referenced from:
      _main in cv-c462f9.o
  "vtable for cv::FlannBasedMatcher", referenced from:
      cv::FlannBasedMatcher::~FlannBasedMatcher() in cv-c462f9.o
  NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

pkg-config --libs --cflags opencv

-I/usr/local/include/opencv -I/usr/local/include -L/usr/local/lib -lopencv_dnn -lopencv_ml -lopencv_objdetect -lopencv_shape -lopencv_stitching -lopencv_superres -lopencv_videostab -lopencv_calib3d -lopencv_features2d -lopencv_highgui -lopencv_videoio -lopencv_imgcodecs -lopencv_video -lopencv_photo -lopencv_imgproc -lopencv_flann -lopencv_core

g++ cv.cpp -I"/usr/local/Cellar/opencv/3.4.1_5/include" -L"/usr/local/Cellar/opencv/3.4.1_5/lib/" pkg-config --libs --cflags opencv -o cv

clang: error: unsupported option '--libs'
clang: error: unsupported option '--cflags'
clang: error: no such file or directory: 'pkg-config'
clang: error: no such file or directory: 'opencv'