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code: written in c++

following error is shown during ouput

OpenCV Error: Assertion failed ((unsigned)(i1 * DataType<_Tp>::channels) < (unsigned)(size.p[1] * channels())) in cv::Mat::at, file c:\users\administrator\documents\opencv\build\include\opencv2\core\mat.inl.hpp, line 918

please help me out

 #include <iostream>
    #include <opencv2/opencv.hpp>
    using namespace std;
    using namespace cv;
    // Function declarations
    void drawAxis(Mat&, Point, Point, Scalar, const float);
    double getOrientation(const vector<Point> &, Mat&);
    void drawAxis(Mat& img, Point p, Point q, Scalar colour, const float scale = 0.2)
    {
        double angle;
        double hypotenuse;
        angle = atan2((double)p.y - q.y, (double)p.x - q.x); // angle in radians
        hypotenuse = sqrt((double)(p.y - q.y) * (p.y - q.y) + (p.x - q.x) * (p.x - q.x));
        //    double degrees = angle * 180 / CV_PI; // convert radians to degrees (0-180 range)
        //    cout << "Degrees: " << abs(degrees - 180) << endl; // angle in 0-360 degrees range
        // Here we lengthen the arrow by a factor of scale
        q.x = (int)(p.x - scale * hypotenuse * cos(angle));
        q.y = (int)(p.y - scale * hypotenuse * sin(angle));
        line(img, p, q, colour, 1, CV_AA);
        // create the arrow hooks
        p.x = (int)(q.x + 9 * cos(angle + CV_PI / 4));
        p.y = (int)(q.y + 9 * sin(angle + CV_PI / 4));
        line(img, p, q, colour, 1, CV_AA);
        p.x = (int)(q.x + 9 * cos(angle - CV_PI / 4));
        p.y = (int)(q.y + 9 * sin(angle - CV_PI / 4));
        line(img, p, q, colour, 1, CV_AA);
    }
    double getOrientation(const vector<Point> &pts, Mat &img)
    {
        //Construct a buffer used by the pca analysis
        int sz = static_cast<int>(pts.size());
        Mat data_pts = Mat(sz, 2, CV_64FC1);
        for (int i = 0; i < data_pts.rows; ++i)
        {
            data_pts.at<double>(i, 0) = pts[i].x;
            data_pts.at<double>(i, 1) = pts[i].y;
        }
        //Perform PCA analysis
        PCA pca_analysis(data_pts, Mat(), CV_PCA_DATA_AS_ROW);
        //Store the center of the object
        Point cntr = Point(static_cast<int>(pca_analysis.mean.at<double>(0, 0)),
            static_cast<int>(pca_analysis.mean.at<double>(0, 1)));
        //Store the eigenvalues and eigenvectors
        vector<Point2d> eigen_vecs(2);
        vector<double> eigen_val(2);
        for (int i = 0; i < 2; ++i)
        {
            eigen_vecs[i] = Point2d(pca_analysis.eigenvectors.at<double>(i, 0),
                pca_analysis.eigenvectors.at<double>(i, 1));
            eigen_val[i] = pca_analysis.eigenvalues.at<double>(0, i);
        }
        // Draw the principal components
        circle(img, cntr, 3, Scalar(255, 0, 255), 2);
        Point p1 = cntr + 0.02 * Point(static_cast<int>(eigen_vecs[0].x * eigen_val[0]), static_cast<int>(eigen_vecs[0].y * eigen_val[0]));
        Point p2 = cntr - 0.02 * Point(static_cast<int>(eigen_vecs[1].x * eigen_val[1]), static_cast<int>(eigen_vecs[1].y * eigen_val[1]));
        drawAxis(img, cntr, p1, Scalar(0, 255, 0), 1);
        drawAxis(img, cntr, p2, Scalar(255, 255, 0), 5);
        double angle = atan2(eigen_vecs[0].y, eigen_vecs[0].x); // orientation in radians
        return angle;
    }
    int main(int, char** argv)
    {
        // Load image
        //    Mat src = imread("pca_test1.jpg");
        Mat src = imread(argv[1]);
        // Check if image is loaded successfully
        if (!src.data || src.empty())
        {
            cout << "Problem loading image!!!" << endl;
            return EXIT_FAILURE;
        }
        imshow("src", src);
        // Convert image to grayscale
        Mat gray ...